Category: Email Strategy

To unsubscribe means to remove yourself from a mailing list, service or subscription so you stop receiving its messages or deliveries. In email, unsubscribing is the formal opt out: you click a link or button, and in most countries the sender is legally required to stop marketing to you within a set number of days.

Unsubscribe Definition

If you want to define unsubscribe in one line, it is the act of cancelling a subscription you previously agreed to. Dictionaries list it as a verb with two closely related senses:

1. To cancel a subscription to a publication, service or membership.
2. To remove your address from a mailing list so you no longer receive emails, newsletters or alerts from that sender.

The second sense is the one most people mean today. When you unsubscribe from an email list, you aren’t deleting your account or your relationship with the company. You’re telling them to stop sending a specific kind of message, usually marketing.

It’s pronounced un-sub-SCRIBE, with the stress on the last syllable. The forms are what you’d expect: unsubscribe, unsubscribes, unsubscribed, unsubscribing.

“Unsubscribe” as a noun

People who work in email marketing also use the word as a noun. “We got 40 unsubscribes on yesterday’s campaign” is perfectly normal shop talk, even if a dictionary would prefer “unsubscriptions.” You’ll see this noun form in every email platform’s reporting dashboard, usually next to opens, clicks and bounces.

Unsubscribe vs. unsubscribe from

The verb almost always takes “from” when you name the list or sender: you unsubscribe from a newsletter. Without an object, it stands alone: “I finally unsubscribed.” Writing “unsubscribe the newsletter” without “from” reads as an error to most native speakers.

Examples of Unsubscribe in a Sentence

Seeing the word used in context helps, especially if English isn’t your first language.

• “I unsubscribed from three store newsletters this morning, and my inbox already feels lighter.”
• “If you no longer wish to receive these emails, you can unsubscribe at any time.”
• “She meant to unsubscribe but hit the spam button instead.”
• “Our unsubscribe rate jumped after we started sending daily.”
• “Text STOP to unsubscribe from order alerts.”
• “He unsubscribed from the streaming service once the free trial ended.”
• “Unsubscribing won’t close your account; you’ll still receive receipts and password resets.”

That last example matters more than it looks. It describes exactly how email opt out works in practice, which the rest of this article covers.

Where the Word Comes From

“Unsubscribe” is built from two parts: the prefix un- (reverse or undo) and subscribe. “Subscribe” comes from the Latin subscribere, meaning “to write underneath.” Originally, to subscribe was to sign your name at the bottom of a document, which is how you pledged support or money for something.

That idea of signing up stretched over the centuries to cover magazines, newspapers and memberships. Paying for a regular delivery became “subscribing.” Undoing that agreement became “unsubscribing.”

Email gave the word its biggest boost. Once mailing lists and newsletters went mainstream online, “unsubscribe” turned into one of the most clicked words on the internet. It sits at the bottom of nearly every marketing email you receive.

Other Words for Unsubscribe

There’s no perfect one-word synonym, because “unsubscribe” carries the specific idea of leaving a list you joined. These come closest:

Term	Where you’ll see it	Meaning
Opt out	Email, SMS, privacy settings	Choose to stop receiving something; the legal term in most regulations
Unsub	Casual talk, marketer slang	Short for unsubscribe
Cancel subscription	Paid services, apps, magazines	Stop a paid or recurring plan
Remove me from your list	Reply-based requests	A plain-English way to ask a sender to stop
Withdraw consent	GDPR and privacy notices	Take back permission you previously gave
Unfollow	Social media	Stop seeing someone’s posts in your feed
Leave (a group or list)	Discussion lists, community forums	Exit a mailing list or group

“Opt out” is the term you’ll meet most often in laws and policies, which is why “email opt out” and “unsubscribe” are used interchangeably. Its opposite, “opt in,” means you actively agreed to receive messages.

Unsubscribe vs. Opt Out vs. Spam vs. Block

These four actions look similar from your side of the inbox. They mean very different things to the sender and to your email provider.

Action	What you’re telling the world	What happens next
Unsubscribe	“Stop sending me this, please.”	Sender adds you to a suppression list and stops marketing emails
Opt out	Same as unsubscribe, often broader (can cover SMS, data sharing or all marketing)	Sender records the preference across the channels named
Mark as spam	“I never wanted this” or “This is junk.”	Your provider files a complaint, and the sender’s reputation takes a hit
Block	“I don’t want to see anything from this address.”	Your mail app filters future messages; the sender usually isn’t told

If the sender is a legitimate company you signed up with, unsubscribing is the fairer choice. Marking a real newsletter as spam damages that sender’s ability to reach everyone else, which is part of how e-mail spam filtering learns what to filter.

Blocking is the better tool for a person or address that keeps writing to you directly. If you just want old promos gone, you can bulk delete Gmail emails from that sender after you unsubscribe.

How Email Opt Out Works

From your side, unsubscribing usually takes a few seconds.

The two places you’ll find an unsubscribe option

The footer link. Almost every marketing email has an unsubscribe link at the bottom, often in small grey text next to the company’s postal address. Clicking it opens a web page that confirms your removal or asks you to choose what to stop.

The inbox button. Gmail, Yahoo Mail, Apple Mail and Outlook can show an Unsubscribe option near the top of the message, beside the sender’s name. This button doesn’t come from the email’s visible content. It’s powered by a hidden header the sender includes, and it’s usually the fastest route because nothing opens in your browser.

Gmail also added a Manage subscriptions view in 2025. It groups your senders by how often they email and lets you unsubscribe from several in one place.

What’s happening behind the button

That inbox button relies on the List-Unsubscribe header. A modern, compliant setup looks like this:

List-Unsubscribe: <https://example.com/unsubscribe?id=abc123>, <mailto:[email protected]?subject=unsubscribe>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

The first line gives mail apps two ways to process the request: a web address and an email address. The second line, defined in RFC 8058, tells the provider it can unsubscribe you with a single background request. No landing page, no login, no “Are you sure?” screen.

When you click the button, your email provider sends that request to the sender’s system. The sender’s platform then flags your address as unsubscribed, and many platforms fire a webhook so the company’s other tools (a CRM or online store, for example) update at the same time.

Your address isn’t deleted. It’s suppressed.

This surprises a lot of people. A well-run sender doesn’t erase your address when you unsubscribe. It moves you onto a suppression list, a record of addresses that must never receive marketing again.

That sounds backwards, but it protects you. If the company deleted you outright and later imported an old spreadsheet, you’d be back on the list. Suppression stops that from happening.

The Rules Senders Have to Follow

An unsubscribe link isn’t a courtesy. It’s required by law in most major markets and by the big mailbox providers.

United States: CAN-SPAM

Under the CAN-SPAM Act, enforced by the Federal Trade Commission, commercial emails must:

• Include a clear way to opt out of future messages.
• Honor opt-out requests within 10 business days.
• Keep the opt-out mechanism working for at least 30 days after the email is sent.
• Not charge a fee, ask for any information beyond your email address, or make you do more than reply or visit a single page.
• Not sell or transfer your address once you’ve opted out.

Penalties run to more than $50,000 per violating email, and the FTC adjusts the figure for inflation each year.

Gmail and Yahoo (February 2024)

Google and Yahoo announced new bulk sender rules in October 2023 and began enforcing them in February 2024. Anyone sending more than 5,000 messages a day to Gmail addresses must:

• Support one-click unsubscribe through the List-Unsubscribe and List-Unsubscribe-Post headers (the deadline for this part was extended to June 1, 2024).
• Process unsubscribe requests within 2 days.
• Keep spam complaint rates below 0.3%, with Google recommending under 0.1%.

Two days is far stricter than CAN-SPAM’s 10 business days. Large senders now treat it as the real deadline.

Microsoft Outlook (May 2025)

Microsoft followed in May 2025 with requirements for senders mailing more than 5,000 messages a day to Outlook.com, Hotmail and Live addresses. The headline rules cover authentication (SPF, DKIM and DMARC), and Microsoft also expects a working, easy-to-find unsubscribe option.

Europe, the UK and Canada

• GDPR (EU) and UK GDPR: Withdrawing consent must be as easy as giving it, and people have an absolute right to object to direct marketing. Marketing rules for email sit alongside GDPR in the ePrivacy framework and, in the UK, PECR.
• CASL (Canada): Unsubscribe requests must be processed within 10 business days, and the mechanism must stay valid for at least 60 days after sending.

Why People Unsubscribe

Every unsubscribe is feedback. These are the reasons that come up again and again:

• Too many emails. Frequency is the reason readers cite most often. A brand that jumps from weekly to daily sends will see unsubscribes climb.
• Content that doesn’t match the promise. Someone signed up for recipes and started getting coupons.
• No longer relevant. They bought the product, moved house, changed jobs or outgrew the topic.
• They never meant to sign up. Pre-ticked boxes and checkout opt-ins create subscribers who leave at the first email.
• Inbox cleanup. Some people do a seasonal purge and unsubscribe from dozens of senders in one sitting.
• Privacy concerns. A data breach or an uncomfortably personal email can make someone want out.

Notice that only one of those reasons is “they don’t like you.” Most unsubscribes are about timing, volume or fit.

What Happens When Someone Unsubscribes

For the sender, an unsubscribe triggers a chain of events:

1. The address is flagged as unsubscribed in the email platform.
2. It’s added to the suppression list, so future campaigns skip it automatically.
3. Connected tools sync the change, if the integrations are set up.
4. The unsubscribe shows up in campaign reports, tied to the email that prompted it.

What doesn’t happen is just as important. The person can still receive transactional emails, such as receipts, shipping updates and password resets. These aren’t marketing, so opt-out laws don’t cover them. Sneaking promotions into those messages, though, can turn them back into commercial email in the eyes of regulators.

What counts as a normal unsubscribe rate

A small number of unsubscribes on every send is healthy. Mailchimp’s widely cited industry benchmarks put the average unsubscribe rate at roughly 0.26% per campaign, which works out to about 26 people for every 10,000 delivered. Treat any benchmark as a rough guide, since your audience, industry and sending frequency all shift the number.

What matters more is change over time. If your rate doubles after one campaign, look at what was different: the subject line, the offer, the send day, or a sudden jump in frequency. Running A/B testing on frequency and content is a cleaner way to find the cause than guessing.

Making Unsubscribe Work for You as a Sender

If you run a list, it’s tempting to see every unsubscribe as a loss. In practice, an easy opt out is one of the best things you can do for deliverability. People who want to leave will leave either way. You get to choose whether they click “unsubscribe” or “report spam.”

A few practices separate good senders from frustrating ones:

• Put the link where people can find it. Footer is standard. Tiny, low-contrast text or a link labelled “manage” instead of “unsubscribe” just creates spam complaints.
• Offer a preference center, but don’t force it. Let people choose fewer emails or specific topics. Always include a one-click “unsubscribe from all” option on the same page.
• Confirm the opt out in one step. Don’t ask people to type their email address or log in. CAN-SPAM limits what you can ask for, and Gmail’s one-click rule removes the page entirely for header-based requests.
• Never email to confirm an unsubscribe. A “Sorry to see you go!” email after someone opts out is another unwanted message. Show a confirmation on the web page instead.
• Send from an address people recognize. Readers who know who you are are more likely to unsubscribe than to report you. A consistent custom domain email address helps with that trust.

Once you’ve got the basics right, unsubscribes become useful data that plugs into the wider practice of email marketing, telling you which content earns attention and which wears it out.

When You Shouldn’t Click Unsubscribe

Unsubscribing works when the sender is legitimate. With genuine spam, it can backfire.

If an email arrived from a company you’ve never heard of, with no clear business name or postal address, the “unsubscribe” link may be a trap. Clicking it can confirm your address is active, which makes it more valuable to spammers. Some links lead to phishing pages designed to collect passwords.

For those messages, use your email app’s Report spam or Report phishing button and move on. Save the unsubscribe link for brands you actually signed up with, such as a shop you bought from, a newsletter you joined, or a service you use.

How Opt Out Works for Text Messages

SMS has its own unsubscribe system built around keywords. Reply STOP to almost any marketing text in the US and you’ll be removed. Other commonly accepted words include UNSUBSCRIBE, CANCEL, END and QUIT.

FCC rules that took effect in April 2025 strengthened this. Consumers can revoke consent through any reasonable means, including words like “revoke” and “opt out,” and senders have to honor those requests within 10 business days. Most businesses send one final text confirming you’ve been removed, and that’s allowed.

To resubscribe, reply START or UNSTOP to the same number.

FAQ

What does it mean to unsubscribe from an email?

It means asking a sender to stop emailing you marketing messages. You click the unsubscribe link or button, and the company adds your address to a suppression list. You’ll usually still receive account-related messages such as receipts and password resets, because those aren’t marketing.

How to subscribe again after unsubscribe?

Go back to the company’s website and sign up using its newsletter or subscription form, the same way you joined the first time. Some brands also let you rejoin from your account settings or preference center. Because your address sits on a suppression list, a fresh sign-up is often the only way to lift it, and some platforms will send you a confirmation email to prove you really want back in.

What is another term for “unsubscribe”?

“Opt out” is the closest equivalent and the term used in most laws and privacy policies. Other options include “unsub” (casual), “cancel your subscription” (for paid services), “withdraw consent” (privacy and GDPR language) and “remove me from your list.”

What to text to unsubscribe?

Reply STOP to the number that texted you. Most US senders also accept UNSUBSCRIBE, CANCEL, END and QUIT. You should get one confirmation text, and after that the marketing messages should stop. Reply START if you ever want to rejoin.

How long does it take for unsubscribe to work?

In the US, CAN-SPAM gives senders up to 10 business days. Large senders mailing Gmail and Yahoo users must process requests within 2 days, and most email platforms apply the opt out instantly. If you still get emails after two weeks, report the messages as spam.

Does unsubscribing delete my account?

No. Unsubscribing only stops a particular type of email, usually marketing. Your account, order history and saved details stay in place. To delete your account, look for an account deletion or privacy option in the company’s settings, or contact its support team.

A/B testing means sending two versions of an email to separate, random groups of your list and measuring which one performs better. This guide covers how to choose what to test, how many subscribers you need, how to read the results without fooling yourself, and how to keep a test from damaging your deliverability.

What is A/B testing?

An A/B test is a controlled experiment. You take one element of an email, create two versions of it, and send each version to a randomly chosen group of subscribers. Everything else stays the same. Because the only difference between the groups is the element you changed, any reliable difference in results comes from that change.

The terminology varies. A/B split testing, an ab split test, a b testing, a & b testing, and the occasional “a to b test” all describe the same method. A/B tests can compare more than two versions (A/B/C or A/B/n tests), but the principle is unchanged: one variable, random groups, one metric that decides the winner.

Email is one of the easiest places to run experiments. You control the audience, the send happens all at once, and results usually arrive within a day. Websites need traffic to build up over weeks. A campaign to 20,000 subscribers can produce a usable answer before lunch the following day.

If you’re new to the channel, our guide to what email marketing is and how it actually works covers the basics. This article assumes you already send campaigns and want to improve them with evidence instead of guesswork.

A/B testing vs multivariate testing

A multivariate test changes several elements at once and tests every combination. If you test two subject lines and two hero images, you get four versions. Add two call-to-action buttons and you have eight.

Multivariate tests show how elements interact, but each combination gets a smaller share of the list. Most email lists can’t support that. A list of 10,000 split eight ways gives each version only 1,250 people, which is rarely enough to detect anything except a very large difference. Run A/B tests until your list is in the hundreds of thousands. After that, multivariate testing becomes practical.

A/B testing terminology 101

You’ll see these terms in your email service provider’s reports and in any testing tool. Learn them once and the reports become much easier to read.

• Control (A): The current version, or the one you’d send if you weren’t testing.
• Variant (B): The version with the single change you’re testing.
• Hypothesis: A specific, falsifiable prediction. “A subject line with the discount amount will lift click rate because subscribers scan for value” is a hypothesis. “Let’s try a new subject line” isn’t.
• Primary metric: The one number that decides the winner. Choose it before you send.
• Guardrail metric: A number you watch to make sure the winner isn’t causing harm somewhere else, such as unsubscribes or spam complaints.
• Sample size: How many recipients each version needs before a difference can be trusted.
• Minimum detectable effect (MDE): The smallest lift you want the test to be able to detect. Smaller lifts need far larger samples.
• Statistical significance: How confident you can be that the difference isn’t random chance. Marketers usually work at 95% confidence, which corresponds to a p-value below 0.05.
• Statistical power: The probability that your test detects a real effect of the size you specified. Eighty percent is the usual standard.
• Holdout group: A slice of the audience that receives nothing, or the old experience, so you can measure the total impact of a program.
• Test-then-send: A setup where your ESP sends variants to a small sample, waits, and then sends the winning version to everyone else.

Why open rate stopped being a reliable winner

This is the most common mistake in email testing, so it gets its own section before the how-to.

In September 2021, Apple released Mail Privacy Protection (MPP) with iOS 15. When MPP is enabled, Apple Mail preloads remote content, including tracking pixels, through proxy servers. Your ESP records an “open” whether or not the person actually read the email. Apple Mail is a large share of opens on many consumer lists, so a significant portion of your open data is now generated by machines.

This creates two problems for A/B tests:

1. Opens are inflated and noisy. The real difference between two subject lines is mixed with automated opens that have nothing to do with the subject line.
2. Body content can’t influence the pixel fire. If your test changes anything inside the email, open rate is the wrong metric because it’s recorded before anyone sees the content.

Subject line tests can still be judged on opens, but only with caution. Some ESPs let you exclude Apple’s machine opens from reports, which helps. A better approach is to judge subject line tests on clicks or conversions, which are much harder to fake, and to treat opens as a secondary signal.

A/B testing metrics to measure

Choose the metric that sits closest to the outcome the change could affect. This table pairs common email tests with the metric that should decide them and the guardrail to watch.

What you’re testing	Primary metric	Secondary signal	Guardrail metric
Subject line / preheader	Click rate (per recipient)	Open rate (MPP-adjusted)	Spam complaint rate
From name	Click rate	Open rate	Unsubscribe rate
Body copy or layout	Click-to-open rate or click rate	Clicks per link	Unsubscribe rate
Call to action	Click rate on the CTA	Conversion rate	None usually needed
Offer or discount	Revenue per recipient	Conversion rate	Margin per order
Send time / day	Click rate	Conversions within 48 hours	Complaint rate
Email length or frequency	Revenue per recipient over weeks	Click rate	Unsubscribes, complaints

Revenue per recipient is the strongest metric for anything commercial. It accounts for both how many people bought and how much they spent, and it uses the full send as the denominator, so a version that gets fewer clicks but larger orders can still win.

What you need before your first A/B test

Set up these prerequisites before you send a test. Without them, results will be unreliable.

• An ESP with a built-in A/B feature. Nearly every mainstream email service provider has one, though it’s often limited to paid plans. If you’re unsure what your platform handles for you, our explainer on what an ESP does in email marketing covers it.
• A list large enough for the effect you want to detect. The sample size table later in this guide shows the numbers. As a rough minimum, you want at least a few thousand recipients per variant for click-based tests.
• Click and conversion tracking. UTM parameters on links and a connected store or analytics setup, so you can measure revenue as well as clicks.
• An authenticated sending domain. Both variants must send from the same properly authenticated domain email address with SPF, DKIM and DMARC in place. Otherwise, a deliverability difference can be mistaken for a creative difference.
• A written hypothesis and a single primary metric. Write them down before you build anything.
• A test log. A spreadsheet works fine. The archive section below includes a template.

How to prioritize A/B test hypotheses

Most teams have more ideas than send volume. Every test uses part of your list, so prioritizing matters as much as running the test well.

The ICE framework, popularized by growth marketer Sean Ellis, is a simple way to rank ideas. Score each hypothesis from 1 to 10 on three questions:

• Impact: If this wins, how much will it move the primary metric?
• Confidence: How much evidence do you already have that it will work, from past tests, customer research or competitor patterns?
• Ease: How quickly can you build and send it?

Average the three scores and test the highest-ranking ideas first. The PIE framework (Potential, Importance, Ease), developed at the optimization agency WiderFunnel, works the same way with slightly different questions. Choose one and use it consistently so scores are comparable over time.

Two rules improve any scoring method. First, give high priority to emails that go out repeatedly, such as welcome emails, abandoned cart flows and weekly newsletters. A winner there pays off on every future send, while a winner on a one-off promotion is used once. Second, give high priority to bigger changes. A completely different offer is more likely to produce a detectable difference than a slightly different button color.

What to test first in email

Here are some example hypotheses, roughly ordered by how much they tend to matter:

1. The offer itself. Free shipping vs 15% off. A bundle vs a single product. This usually matters more than any wording change.
2. Subject line approach. Benefit-led (“Your skin, 3 weeks from now”) vs curiosity (“We changed the formula”) vs plain (“New: Vitamin C serum”).
3. From name. Brand name vs a person at the brand (“Maya at Brightleaf”).
4. Primary call to action. One button vs several links. “Shop the sale” vs “See what’s 30% off.”
5. Email length. A short email that sends readers to a landing page vs a longer email that does the selling itself.
6. Personalization. Product recommendations based on browsing vs bestsellers.
7. Send time and day. Useful, but usually lower impact than most people expect.
8. Design details. Image-heavy vs mostly text, button color, layout. Test these last.

How to set up A/B tests in email: step by step

Step 1: Write a hypothesis and choose one metric

Use this format: “If we change [element] from [A] to [B], then [primary metric] will increase, because [reason].” The “because” is important. It makes you state what you think you’ll learn about your customers, so a losing test still teaches you something.

Then choose one primary metric from the table above. If you check five metrics after the send and choose whichever one looks good, you’re very likely to find a false winner.

Step 2: Calculate the sample size

Most email tests fail at this step. Decide the smallest lift you’d act on, check your baseline rate, and use the table in the next section or an online calculator such as Evan Miller’s free sample size tool. If your list can’t reach the required size in one send, either test a bigger change or run the same test across several sends and combine the results.

Step 3: Build the control and one variant

Duplicate the email, then change only the element named in your hypothesis. Preview both versions on mobile and desktop, then send test copies to yourself. A broken merge tag in one variant will invalidate the test. If one goes out anyway, our guide on handling a typo email after it’s sent explains how to deal with it.

Step 4: Choose your split method

You have two main options:

• Full 50/50 split. Half the list gets A, half gets B. This gives maximum statistical power, and it’s the only valid option for send-time tests, since the time is the thing you’re testing. You learn the most, but the losing version reaches half your list.
• Test-then-send. A sample (for example 10% to A and 10% to B) receives the test, the ESP waits a set time, then sends the winner to the remaining 80%. More people see the better version, but the test sample is smaller, so only large differences reach significance.

For learning, use a full split. For maximizing a single campaign’s results with a large list, use test-then-send.

Step 5: Set the winner criterion and wait time

In your ESP, choose the winning metric (clicks or revenue where available) and the wait period before the remainder sends. Short waits favor people who check email immediately, who aren’t representative of the whole list. Wait at least four hours. For click and revenue metrics, waiting closer to 24 hours is safer if the campaign isn’t time-sensitive.

Step 6: Send and leave it alone

Don’t stop the test early because one version is ahead after an hour. Early leads often disappear. Checking results repeatedly and stopping the moment you see significance greatly inflates your false-positive rate. This problem is called “peeking,” and it’s a well-documented issue in experimentation.

Step 7: Analyze, record and roll out

Read the results using the process in the analysis section below. Record them in your test log, then apply what you learned. If the winning email is a recurring template, update the template.

How big does each group need to be?

The table below gives approximate recipients needed per variant. It uses the standard two-proportion formula at 95% confidence and 80% power. “Relative lift” means the improvement as a percentage of the baseline, so a 20% lift on a 2% click rate means going from 2.0% to 2.4%.

Baseline rate	10% relative lift	20% relative lift	50% relative lift
0.5% (purchase rate per recipient)	~327,600	~85,800	~15,600
2% (typical click rate)	~80,600	~21,100	~3,800
5% (strong click rate)	~31,200	~8,100	~1,500
30% (open rate, MPP caveats apply)	~3,800	~960	~160

Figures calculated by Email Marketing Voodoo using n ≈ 7.84 × [p₁(1−p₁) + p₂(1−p₂)] ÷ (p₁ − p₂)², rounded.

Two things stand out. First, purchase-rate tests need very large samples unless the change is dramatic. Second, the reason open-rate tests used to seem easy is that open rates are high, so even small lists produced “significant” results. MPP has made many of those results unreliable.

If you have 5,000 subscribers and a 2% click rate, a full 50/50 split gives you about 2,500 per variant. That’s enough to detect roughly a 50% lift and nothing smaller. So test bold changes. Two subject lines that differ by a single word won’t produce a readable result.

A/B testing features in popular email platforms

Every major ESP includes A/B testing, but they differ in what you can test and on which plans. This is how the main platforms handle it as of early 2025. Plans and limits change, so check your provider’s current pricing page before upgrading for this feature.

Platform	What you can test	How the winner is picked	Plan notes
Mailchimp	Subject line, from name, content, send time (up to 3 versions)	Opens, clicks, revenue, or manual	A/B on paid plans; multivariate (up to 8 combinations) on Premium
Klaviyo	Subject line, preview text, content, send time; split tests inside flows	Open or click rate for campaigns; manual review in flows	Available on campaign and flow tools
Kit (formerly ConvertKit)	Subject lines on broadcasts	Highest open rate; sample receives test, winner goes to the remaining 70% after 4 hours	Subject line testing only
HubSpot	Subject line, content, sender	Chosen metric after a set test period	Marketing Hub Professional and above
Brevo	Subject line, content	Open or click rate	Higher-tier plans; not on entry plans

If your platform only judges winners on opens (Kit, for example), use the automatic winner for subject-line tests only. Then check click data in the report yourself before treating the result as a lesson.

How to analyze A/B test results

Here’s a worked example. You test two subject lines with a full split of 20,000 subscribers.

• Version A: 10,000 recipients, 230 clicks (2.3%)
• Version B: 10,000 recipients, 250 clicks (2.5%)

B looks about 9% better. A two-proportion z-test gives a z-score of about 0.92 and a p-value around 0.36. You can’t call a winner. A difference this size will appear by chance fairly often with these sample sizes. The correct conclusion is “no detectable difference,” and you should record it that way.

Now suppose B had received 290 clicks (2.9%). The z-score rises to about 2.67, with a p-value around 0.008. That’s well past the 95% threshold, so you can be reasonably confident B is better.

Use this checklist for every analysis:

1. Check the primary metric first. Is the difference significant at the level you set in advance? Most ESP reports show this. If yours doesn’t, any free significance calculator will do it with four numbers.
2. Look at the confidence interval, not only the winner. A result of “B is better by somewhere between 0.5% and 40%” tells you much more than “B won.”
3. Check guardrails. If B won on clicks but doubled unsubscribes or complaints, it didn’t win.
4. Check that the split was valid. Both groups should have similar sizes and similar delivery rates. If B had a much higher bounce or block rate, you’ve found a deliverability problem, not a creative one.
5. Segment cautiously. It’s fine to check whether the result held for new vs long-time subscribers. Treat segment-level “wins” as new hypotheses to test, not conclusions. Slice the data enough ways and something will look significant by chance.
6. Write down why you think it won or lost. This becomes useful across dozens of tests.

Keep your A/B tests from hurting deliverability

Most testing guides skip this, but it matters. A test that wins on clicks can still damage your sender reputation if it attracts spam complaints. Mailbox providers now enforce strict limits.

Mailbox provider	Rules in effect from	Applies to	Requirements relevant to testing
Gmail	February 2024 (one-click unsubscribe enforced from June 2024)	Senders of 5,000+ messages a day to personal Gmail accounts	SPF and DKIM, DMARC policy, alignment, one-click unsubscribe, spam rate under 0.3%
Yahoo	February 2024	Bulk senders	SPF and DKIM, DMARC policy, one-click unsubscribe, low complaint rate
Microsoft (Outlook.com, Hotmail, Live)	May 5, 2025	Senders of 5,000+ messages a day	SPF, DKIM, DMARC at minimum p=none aligned with SPF or DKIM; noncompliant mail rejected

Google’s guidance also asks senders to keep spam rates below 0.1% and never reach 0.3%. An aggressive subject line variant can raise complaints for that send. If that variant is then sent to the rest of the list as the “winner,” it affects your entire domain’s reputation.

Both variants should send from the same authenticated domain so the creative is the only variable. At minimum, your DMARC record should look something like this:

_dmarc.example.com.  TXT  "v=DMARC1; p=none; rua=mailto:[email protected]"

Also avoid testing two different sending domains or IPs against each other as if it were a content test. Inbox placement varies by domain, so you’d be comparing filter outcomes, not creative. If you want to understand why one variant might land in spam when the other doesn’t, our guide to how email spam filters work and why messages get caught covers the filtering signals involved.

Testing automated flows and using holdout groups

Campaign tests are useful, but automated emails are where results compound. A welcome series or abandoned cart flow can run for years and reach every new customer, so one winner there can outperform dozens of campaign wins.

Flow tests work differently from campaign tests:

• They run continuously. Instead of one send, recipients are split as they enter the flow. Set a fixed duration or sample size in advance and stop when you reach it.
• They can test structure, not only content. Two emails vs three. A one-hour delay vs a 24-hour delay. A discount in the first reminder vs the last.
• They should use revenue per recipient. A cart reminder that gets fewer clicks but recovers more orders is the winner.

A holdout group answers a bigger question: does this program work at all? Send nothing to a random 5 to 10% of eligible subscribers and compare their purchase rate with everyone who received the flow. Many teams find their post-purchase or win-back flows aren’t producing much additional revenue. Others confirm their welcome series is worth expanding. Either way, you’ll know whether the program is adding value or only taking credit for sales that would have happened anyway.

How to improve A/B test results

If your tests keep ending with “no significant difference,” the cause is almost always one of these:

1. The changes are too small. Changing “Shop now” to “Shop today” won’t produce a measurable difference on a 10,000-person list. Test different ideas, not different wording.
2. The metric is too far from the change. A subject line affects opens and clicks first. Judging it on purchases dilutes the effect with every other factor between the inbox and the checkout.
3. The sample is too small. Combine sends. If you run a newsletter every week, test the same hypothesis across four sends and pool the results.
4. You’re testing the wrong audience. Tests sent to many inactive subscribers mostly measure inactivity. Remove unengaged addresses before testing, or test only on people who’ve engaged in the last 90 days.
5. No customer insight behind the ideas. The best hypotheses come from reply emails, support tickets, reviews and survey responses. “Customers keep asking whether it fits” leads to a much better test than “let’s try an emoji.”

A simple rule makes testing more productive: every test should be able to change a decision. Before sending, ask what you’ll do differently if B wins, and what you’ll do if it loses. If both answers are “nothing,” choose a different test.

Common A/B testing mistakes and how to fix them

Problem	What’s happening	Fix
Winner declared after an hour	Early responders aren’t representative	Wait at least 4 hours; 24 for revenue
“Significant” result that never repeats	Peeking, too many metrics, or too many segments	Pre-register one metric; don’t stop early
Variants have very different delivery rates	Content triggered filtering, or sending infrastructure differed	Check bounces and blocks per variant; send both from the same domain and IP
Open rate winner loses on clicks	MPP inflating opens or curiosity bait	Judge on clicks or revenue
Two changes made at once	You can’t tell which change caused the result	One variable per A/B test
Send-time test run as test-then-send	The winning time has already passed for the remainder	Use a full split for timing tests
Same “winner” fading over weeks	Novelty effect	Re-test important winners a month later
Results never shared	Lessons stay with one person	Keep a shared test log

The novelty effect is often overlooked. A new design or tone can win because it’s different, not because it’s better. Subscribers notice the change, and the lift fades as it becomes familiar. Before you change all templates based on a single win, re-test the result.

How to archive past A/B tests

A test that isn’t recorded will probably be repeated in six months by someone who thinks it’s a new idea. A shared spreadsheet is enough. Use columns like these:

Field	Example entry
Test ID and date	T-014, 12 March
Email / flow	Weekly newsletter
Hypothesis	Naming the discount in the subject lifts clicks because readers scan for value
Variable	Subject line
Audience and split	Engaged 90 days, 50/50, 9,800 per variant
Primary metric	Click rate
Result	A 2.1%, B 2.6%, p = 0.02
Guardrails	Unsubscribes flat, complaints flat
Decision	Adopt; re-test in Q3
Lesson	Explicit value beats curiosity for this list

After about twenty entries, review the lesson column. Patterns will appear, such as “our list prefers plain subject lines” or “urgency backfires with repeat buyers.” These patterns are more valuable than any individual result, and they let you plan future tests around your own data instead of generic best practices.

How to do A/B testing: tools and resources

For email, the ESP’s built-in tester handles the split, the send and the winner selection. You’ll also want:

• A sample size and significance calculator. Evan Miller’s free online tools are widely used and reliable.
• Analytics with UTM tracking, so clicks can be followed through to conversions on your site.
• A store integration that reports revenue per campaign and per variant, if you sell online.
• A shared test log as described above.

If your testing expands from email to landing pages, you’ll need dedicated experimentation software. Google Optimize, which was popular for free website testing, was shut down by Google on September 30, 2023, so teams that relied on it have moved to tools such as Optimizely, VWO and AB Tasty. Larger product teams often run server-side experiments, where the variant is chosen on the server before the page loads. This avoids the flicker and ad-blocker issues that browser-based tests can have. For email marketers, the main lesson from website testing is the discipline it requires: decide sample size in advance, use one primary metric, and don’t stop tests early.

For further reading, Trustworthy Online Controlled Experiments by Ron Kohavi, Diane Tang and Ya Xu (Cambridge University Press, 2020) is widely regarded as the standard book on experimentation. It covers the statistical problems that catch most marketers.

A/B testing statistics worth knowing

These are among the most useful published figures on experimentation:

• Most ideas don’t win. In their 2009 paper on online experimentation at Microsoft, Ron Kohavi and colleagues reported that only about one-third of tested ideas improved the metrics they were designed to improve. Expect a similar or lower rate in your own tests.
• Small changes can still produce large wins. In a 2017 Harvard Business Review article, Kohavi and Stefan Thomke described a Bing test where a minor change to how ad headlines were displayed increased revenue by 12%, worth over $100 million a year in the US. An engineer had shelved the idea for months because nobody thought it was important.
• Political campaigns depend on email tests. Bloomberg Businessweek’s reporting on Barack Obama’s 2012 campaign described a team that tested many subject line variations on small segments before each large fundraising email, and found that the winning subject lines raised far more than the weakest ones. Plain, personal subject lines often beat polished ones.

Kohavi’s figure is the most useful for setting expectations. If two out of three tests lose or show no difference, your testing program is normal. The value comes from the occasional large win and from never shipping the losing ideas.

What results to expect

If you test steadily for a quarter, a realistic outcome looks like this. You’ll run 8 to 12 tests. Two to four will produce a clear winner. Most of the rest will be inconclusive, and one might reveal that a change you were about to make everywhere would have hurt performance. Your recurring emails will have improved subject line conventions and better calls to action, and your test log will contain a few lessons specific to your audience.

The gains add up over time. A 15% click lift in a welcome email and a 10% revenue lift in an abandoned cart flow keep paying off on every send after you implement them. Teams that test consistently, record their results, and focus on high-volume emails get far more from A/B testing than teams that occasionally test a subject line.

FAQ

What do you mean by AB testing?

AB testing (also written A/B testing or a/b split testing) is a method of comparing two versions of something by showing each version to a random group and measuring which performs better on a chosen metric. In email, that usually means two versions of a subject line, offer or design sent to separate random segments of your list. The random split is what makes it a test. Without it, you’re comparing different audiences, not different versions.

Is AB testing dead?

No. The open-rate shortcut is what stopped working. Apple’s Mail Privacy Protection made open-based results unreliable for a large share of subscribers, so the quick subject-line tests many marketers used no longer prove much. A/B testing on clicks, conversions and revenue per recipient works as well as it ever did. Some ESPs now add AI-generated variants and automatic optimization, but those features are still built on the same controlled comparison.

Who uses AB testing?

Almost every organization that sends email or runs a website at scale. Ecommerce brands test offers and cart reminders, publishers test headlines and newsletter formats, SaaS companies test onboarding emails, and nonprofits and political campaigns test fundraising appeals. Large tech companies such as Microsoft, Google, Amazon and Netflix run thousands of experiments a year. A small business with a few thousand subscribers can use the same method with bigger, bolder changes.

What is AB testing in healthcare?

In healthcare, the same principle shows up in two ways. Clinical research uses randomized controlled trials, which work the same way as an A/B test: random assignment, a control, and a pre-specified outcome. Health systems also A/B test patient communications such as appointment reminders, screening invitations and vaccination nudges. A 2021 megastudy published in PNAS tested 19 different text-message reminders to encourage flu vaccination and found that the wording affected uptake. Healthcare senders must also keep patient data within privacy rules such as HIPAA in the US, which limits which tools and personalization they can use.

How long should an email A/B test run?

Run it until you reach the sample size you calculated in advance, not until the result looks good. For a single campaign that means the whole send, with at least four hours before choosing a winner and closer to 24 hours for clicks and revenue. For automated flows, set a fixed recipient count or a minimum of two to four weeks so that weekday and weekend behavior are both included.

Can I A/B test with a small list?

Yes, but only for large differences. With 2,000 subscribers and a 2% click rate, you can reliably detect only very large lifts. Test meaningfully different approaches, such as a different offer, a different format, or a personal sender vs brand sender, and combine results across several sends of the same test before drawing conclusions.

Email marketing is the practice of sending commercial or relationship-building emails to people who have given you permission to contact them. It works by collecting opt-in addresses, sending campaigns and automated messages through an email service provider, and measuring what recipients do next. Below you’ll find the definition, the mechanics behind every send, the rules from Gmail, Yahoo and Microsoft, and the habits that keep your emails out of spam.

Email Marketing Definition: What It Actually Means

The plain email marketing definition: using email to promote your products, services or content to a list of people who asked to hear from you. That last part matters most. Without permission, it’s spam, and the law and mailbox providers both treat it that way.

You’ll see a few email marketing definitions floating around. They emphasize different things, and each one is useful:

• Direct marketing definition. Email is a direct channel. You send a message straight to one person’s inbox, with no algorithm deciding whether your followers see it.
• Owned media definition. Your list belongs to you. A social platform can change its reach overnight. Your subscriber list moves with you from one email platform to the next.
• Permission marketing definition. Coined by Seth Godin in his 1999 book Permission Marketing, this view frames email as a privilege the subscriber grants and can revoke with one click.
• Lifecycle definition. Email follows the customer journey: a welcome after signup, a reminder after an abandoned cart, a receipt after purchase, a win-back after months of silence.

To explain email marketing in one sentence to a colleague: you earn someone’s address, then you keep earning their attention with emails worth opening. The selling happens because of the relationship, not instead of it.

What email marketing is not

It isn’t sending one-to-one emails from your Outlook account to prospects. That’s sales outreach, and it runs on different rules and tools. It isn’t buying a list of 50,000 “targeted” addresses either. Purchased lists contain spam traps, dead addresses and people who never agreed to hear from you. Using one is the fastest way to wreck a sending domain.

It also isn’t the same as an internal newsletter sent to staff. That uses similar tools but has no marketing consent issues and very different goals.

How Email Marketing Works, Step by Step

Every functioning email program, from a one-person Etsy shop to a retailer sending millions of messages a week, follows the same seven steps. The scale changes. The sequence doesn’t.

Step 1: Earn permission

Your list starts with a signup form. It might be on your homepage, a checkout page, a pop-up offering 10% off, or a gated guide. The form needs to say what people will receive and roughly how often.

Many senders use double opt-in: after signing up, the subscriber clicks a confirmation link in a follow-up email. You’ll lose a slice of signups to unclicked confirmations. In exchange, you get proof of consent, fewer typo addresses and almost no spam traps. For a brand-new domain, double opt-in is the safer choice.

Step 2: Store contacts in an email service provider

An email service provider (ESP) such as Mailchimp, Klaviyo, Brevo, Kit or MailerLite stores your contacts, builds your emails, sends them through high-volume mail servers and reports on results. You can’t run email marketing from Gmail or Outlook. Those accounts have daily sending caps, no unsubscribe handling and no list management.

The ESP also stores information about each contact: signup date, source, purchase history, location and custom fields like “dog owner” or “wholesale buyer.” That data powers everything personalized you’ll send later.

Step 3: Authenticate your domain

Before your first campaign, you add DNS records that prove your ESP is allowed to send on behalf of your domain. The three essentials are SPF, DKIM and DMARC. Since February 2024, Gmail and Yahoo have required them for bulk senders, and Microsoft followed for Outlook.com in May 2025. The exact records are covered in the deliverability section below.

You also want to send from your own domain ([email protected]), not a free address like [email protected]. Free-mail addresses fail DMARC when sent through an ESP, so mailbox providers will junk or reject them.

Step 4: Segment your list

Segmentation means splitting your list into groups so each person gets relevant emails. Common segments include:

• New subscribers who haven’t bought yet
• Customers who bought in the last 90 days
• People who clicked a specific product category
• Subscribers who haven’t opened or clicked in six months
• Location, for time zones and local offers

A pet store sending one dog-food promotion to its entire list will annoy every cat owner on it. Splitting by past purchases fixes that in about ten minutes of setup.

Step 5: Write and design the email

A marketing email has five parts readers notice: the from name, the subject line, the preheader (the preview text after the subject), the body and the call to action. Design follows from the goal. A product launch might use a hero image and a single “Shop now” button. A founder’s update might be plain text that looks like a personal note.

Step 6: Send and pass the mailbox provider’s judgment

Clicking send hands your message to the ESP’s servers, which then deliver it to Gmail, Outlook, Yahoo, Apple iCloud and corporate mail servers. Each receiving system decides whether your email lands in the inbox, a promotions tab or spam. That decision is the part most beginners never think about, so it gets its own section next.

Step 7: Track results

Your ESP reports deliveries, bounces, opens, clicks, unsubscribes, spam complaints and, if connected to your store, revenue. You use those numbers to decide what to send next, who to send it to, and who to stop emailing. Then the loop starts again.

What Happens After You Click Send

Understanding this path explains most deliverability problems you’ll ever face.

1. Queueing. Your ESP splits your campaign into individual messages, one per recipient, and personalizes each (name, product recommendations, unsubscribe link).
2. Connection. The ESP’s mail server opens an SMTP connection to the recipient’s mail server. Gmail’s servers see the sending IP address first and check its reputation.
3. Authentication checks. The receiving server looks up your SPF record, verifies the DKIM signature and applies your DMARC policy. If the message fails DMARC and your policy says reject, it never arrives.
4. Filtering. The mailbox provider weighs domain reputation, IP reputation, past engagement from this specific user, complaint rates and the content itself. How those filters decide is a topic in its own right, and our explainer on e-mail spam filtering walks through the signals in detail.
5. Placement. If accepted, the message goes to the inbox, a tab such as Gmail’s Promotions, or the spam folder.
6. Event reporting. Every bounce, open and click flows back to your ESP. Many platforms then push those events to your other tools in real time through webhooks, which is how your CRM knows someone clicked within seconds. If that term is new, a quick webhook definition will make your ESP’s integration settings far less confusing.

Opens are tracked with a tiny invisible image in the email. When the image loads, the ESP logs an open. Clicks are tracked by routing each link through the ESP’s redirect domain before sending the reader to your page.

Both methods have limits, and you’ll see why in the metrics section.

Why Email Marketing Is Worth Your Time

Email is old. It’s also where your customers check in every single day. The Radicati Group, a technology market research firm, publishes the most widely cited figures on email usage.

Metric	2023	2027 (forecast)	Source
Worldwide email users	4.37 billion	4.89 billion	Radicati Group, Email Statistics Report 2023–2027
Emails sent and received per day	347.3 billion	408.2 billion	Radicati Group, Email Statistics Report 2023–2027

That’s more than half the planet with an inbox, and the number is still growing.

The main email marketing benefits

You own the audience. If a social network cuts organic reach, your followers vanish behind a paywall. Your email list stays yours. Export it, move platforms, keep sending.

It’s cheap to run. Many ESPs offer free plans for small lists, and paid plans for a few thousand contacts often cost less than a modest ad budget for a single week. Litmus, an email testing company, has put average email ROI at roughly $36 for every $1 spent. Treat that as an industry-wide average, not a promise for your business.

It drives sales directly. A well-timed abandoned-cart email reaches someone who already wanted the product. Few channels let you reach a warm buyer within an hour of hesitation.

It builds loyalty. Regular, useful emails keep you in mind between purchases. A coffee roaster that sends brewing tips and early access to limited lots is building loyalty that discounts alone can’t buy.

It’s measurable. You can track exactly how many people clicked, which link they chose and how much revenue followed. That makes testing easy and decisions concrete.

It’s personal at scale. One template can greet 40,000 people by name, show each of them products related to their last order and arrive at 9 a.m. in their own time zone.

9 Types of Emails You Can Send

People searching for “emails for email marketing” usually want to know what to actually send. These nine types cover nearly every program. Most businesses start with the first three and add the rest over time.

Email type	When it’s sent	Main goal	Automated or manual
Welcome email	Right after signup	Set expectations, deliver the promised offer	Automated
Newsletter	Weekly or monthly	Keep subscribers engaged with useful content	Manual
Promotional campaign	Sales, launches, seasonal events	Drive sales	Manual
Abandoned cart	1–24 hours after a cart is left	Recover the sale	Automated
Transactional	After a purchase, signup or password reset	Confirm an action	Automated
Post-purchase follow-up	Days after delivery	Reviews, how-to tips, cross-sells	Automated
Re-engagement (win-back)	After months of inactivity	Revive or remove inactive subscribers	Automated
Announcement	New product, feature or policy	Inform	Manual
Survey or feedback request	After an interaction or periodically	Learn what customers want	Either

The welcome email

This is usually the most-opened email you’ll ever send, because the subscriber just asked for it. Deliver whatever you promised on the signup form immediately: the discount code, the guide, the first lesson. Then tell them what’s coming and how often.

A welcome series of three to five emails over two weeks works better than a single message for most businesses. Use it to tell your story, show bestsellers and answer common objections.

Newsletters

A newsletter is a regular send built around content: tips, news, stories, curated links. It works when it gives readers something they’d miss if it stopped arriving. It fails when it’s a sales flyer with a “newsletter” label.

Promotional campaigns

These are your sales emails: Black Friday offers, product launches, limited stock alerts. Send them to segments that care. A 20% off code for running shoes should go to people who have browsed or bought running gear.

Abandoned cart emails

A shopper adds items, then leaves. An automated email arrives an hour later with the items pictured and a link back to the cart. Many stores add a second reminder at 24 hours, sometimes with free shipping. This is one of the highest-earning automations in ecommerce because the intent is already there.

Transactional emails

Order confirmations, shipping notices, receipts and password resets are transactional. They aren’t marketing under CAN-SPAM as long as their primary purpose is the transaction. Keep promotions inside them minimal, or you risk changing their legal status.

They also get read by machines. Google says Chrome’s autofill can now pull flight and order details from Gmail, which is a strong reason to keep order numbers, dates and addresses in clean, readable text rather than burying them in images.

Re-engagement emails

Subscribers who haven’t opened or clicked in six months drag down your engagement signals. Send them a short series asking if they still want your emails. Anyone who doesn’t respond gets removed. Smaller, engaged lists outperform larger, sleepy ones in the inbox every time.

Email Marketing vs. Marketing Automation

These terms overlap, and people often use them interchangeably. They aren’t the same thing.

Email marketing is the channel: everything you send to subscribers by email, including one-off campaigns you write and schedule by hand.

Marketing automation is the method: software that triggers actions based on rules and behavior. Those actions can include emails, but also SMS messages, CRM updates, lead scoring and ad audience syncing.

Where they meet is the automated email flow. A trigger (signup, purchase, cart abandonment, birthday, inactivity) starts a sequence of emails with delays and conditions between them. “If the customer bought within three days, skip the second reminder” is a typical rule.

Most modern ESPs include basic automation. Dedicated automation platforms such as HubSpot or ActiveCampaign go further with multi-channel journeys and sales-team handoffs. For a small business starting out, the automation built into a standard email platform is plenty. You can graduate later.

A practical split for a new program:

• Automate anything triggered by a person’s own action: welcome, abandoned cart, post-purchase, win-back.
• Send manually anything tied to your calendar: newsletters, sales, launches, announcements.

Set up the automations once, and they earn while you sleep. Spend your weekly writing time on campaigns.

Gmail, Yahoo and Microsoft Sender Rules

In October 2023, Google and Yahoo announced joint requirements for bulk senders, with enforcement starting in February 2024. Microsoft announced matching rules for Outlook.com, Hotmail and Live addresses in April 2025, effective May 5, 2025. If you send marketing email in any real volume, these rules apply to you.

Requirement	Gmail	Yahoo	Microsoft (Outlook.com, Hotmail, Live)
Who it applies to	Senders of about 5,000+ messages a day to personal Gmail accounts	Bulk senders (no fixed public number)	Senders of 5,000+ messages a day to consumer Outlook domains
SPF and DKIM	Required	Required	Required
DMARC	Required, minimum p=none, aligned with SPF or DKIM	Required, minimum p=none	Required, minimum p=none, aligned with SPF or DKIM
One-click unsubscribe	Required for marketing mail (from June 1, 2024)	Required	Functional unsubscribe link expected
Honor unsubscribes	Within 2 days	Within 2 days	Expected promptly
Spam complaint rate	Stay below 0.3%, aim for under 0.1%	Stay below 0.3%	Low complaint rates expected
Enforcement start	February 2024	February 2024	May 5, 2025

Google also says that once you’re classified as a bulk sender, you stay classified, even if your volume later drops.

The DNS records you need

These go into your domain’s DNS settings, usually at your registrar or DNS host. Your ESP will give you the exact values. Here’s what each looks like.

SPF lists the servers allowed to send for your domain. You get one SPF record per domain, so combine all senders into it:

Type: TXT
Host: @
Value: v=spf1 include:_spf.google.com include:spf.your-esp.example ~all

DKIM adds a cryptographic signature to each message. Many ESPs give you a CNAME record that points to a key they manage. Others give you a TXT record like this:

Type: TXT
Host: selector1._domainkey
Value: v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA...

DMARC tells receivers what to do when a message fails authentication and where to send reports. Start at p=none to monitor, then tighten to quarantine and reject once your reports show everything legitimate passes:

Type: TXT
Host: _dmarc
Value: v=DMARC1; p=none; rua=mailto:[email protected]; adkim=r; aspf=r

One-click unsubscribe is handled by two email headers. Your ESP adds them automatically, but it’s worth confirming they’re present in a test message’s raw source:

List-Unsubscribe: <https://example.com/unsubscribe?id=123>, <mailto:[email protected]>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

BIMI is optional. It displays your logo next to your emails in supporting inboxes, including Gmail and Apple Mail. It requires DMARC at p=quarantine or p=reject, and Gmail also needs a Verified Mark Certificate or Common Mark Certificate. Treat it as a later upgrade, not a launch requirement.

The Laws Behind Email Marketing

Spam laws differ by country, and they follow your recipients, not your office. A US store emailing customers in Germany needs to respect GDPR. Here are the three you’re most likely to meet.

Law	Region	Consent model	Key requirements	Maximum penalty
CAN-SPAM Act	United States	Opt-out (consent not required beforehand)	Honest headers and subject lines, identify ads, include a physical postal address, working opt-out honored within 10 business days	Over $50,000 per violating email (inflation-adjusted annually)
GDPR (with ePrivacy rules)	EU and UK (UK GDPR plus PECR)	Opt-in; consent must be freely given, specific, informed and unambiguous	No pre-ticked boxes, record of consent, easy withdrawal	Up to €20 million or 4% of global annual turnover, whichever is higher
CASL	Canada	Opt-in (express or implied consent)	Identify sender, include contact info and unsubscribe, process unsubscribes within 10 business days	Up to CAD $10 million per violation for organizations

A few practical notes:

• CAN-SPAM covers B2B email too. There’s no business-to-business exemption.
• Implied consent under CASL expires. An existing business relationship from a purchase generally counts for two years.
• The UK’s soft opt-in lets you email existing customers about similar products, as long as you offered an opt-out when you collected their address and in every email since.
• Business cards aren’t blanket consent. Under GDPR and CASL, a card handed over at a trade show doesn’t automatically mean someone agreed to your newsletter.

The safe default for any business with international customers: get clear opt-in consent, record when and where it was given, and make unsubscribing a single click.

Choosing the Right Email Marketing Tool

Your ESP choice shapes how easily you can do everything else. Price matters, but it’s rarely the deciding factor for long.

What to look for

• Pricing model. Most platforms charge by contact count. Some charge by emails sent. If you send rarely to a large list, a send-based plan can be cheaper.
• Ecommerce integration. Shopify, WooCommerce or BigCommerce stores need purchase data flowing into the ESP for abandoned cart and product recommendation emails.
• Automation depth. Check for visual flow builders, conditional splits and behavior-based triggers.
• Deliverability support. Look for guided domain authentication, dedicated IP options at higher volume and responsive support.
• Templates and editor. A drag-and-drop editor with mobile preview saves hours each month.
• Reporting. Revenue attribution, click maps and segment-level reporting beat basic open counts.
• Data portability. Make sure you can export your full contact list, including custom fields and consent data.

Free plans to start on

Several well-known ESPs offer free tiers. At the time of writing, Mailchimp’s free plan covers up to 250 contacts with 500 emails per month and a daily cap of 250, Brevo’s free plan allows 300 emails per day, and Kit’s free Newsletter plan supports up to 10,000 subscribers. Free plans change often, so check the current limits on each provider’s pricing page before you commit.

For a side-by-side look at features, costs and who each tool suits, our roundup of small business email platforms compares the main options in detail.

Writing Emails People Actually Open

Design and copy decide whether a delivered email gets read, ignored or reported. Good emails share a handful of habits.

From name and subject line

Your from name should be recognizable instantly. Use your brand name, or “First name at Brand” if you want a personal feel. Keep it consistent so subscribers learn to trust it.

Subject lines work best when they’re specific. “New: the waterproof version of our best-selling jacket” beats “You won’t believe this!” The first tells people what’s inside. The second reads like spam and often gets treated like it.

A few subject line rules worth following:

• Front-load the important words, because mobile clients cut subjects short.
• Avoid ALL CAPS, rows of exclamation marks and fake “RE:” or “FWD:” prefixes. The fake reply trick also breaks CAN-SPAM’s rule against deceptive subject lines.
• Use the preheader to add a second piece of information, not to repeat the subject.

Body copy

Write like a person talking to one customer. Short paragraphs, one main idea, one primary call to action. If you want readers to shop the sale, don’t also ask them to read a blog post, follow you on Instagram and fill out a survey.

Personalization goes far beyond adding a first name. Product recommendations based on browsing, content matched to a subscriber’s stated interests and local event invitations all feel personalized because they’re relevant.

Design

• Design for mobile first. Most opens happen on phones. Use a single-column layout, 14–16px body text and buttons big enough for a thumb.
• Don’t send image-only emails. Some clients block images by default, and filters dislike emails with almost no live text. Keep a healthy balance of text to images.
• Add alt text to every image so the message makes sense when images don’t load and works with screen readers.
• Include a plain-text version. Most ESPs generate one automatically. Check that it reads sensibly.

Plain-text-style emails from a founder or support lead often outperform heavy designs for relationship messages. Close those with a proper sign-off. A clean, human signature makes them feel personal, and you can borrow ideas from our email signature examples.

Proofreading and test sends

Send a test to yourself on desktop and mobile before every campaign. Click every link. Check the personalization fallback, because “Hi {FNAME}” in a live campaign is embarrassing. If a mistake does slip through, a calm correction usually beats silence, and our guide on handling a typo email covers when a follow-up is worth sending.

Metrics to Track (and Which Ones to Trust)

Your ESP will show you dozens of numbers. These are the ones that matter, with reference points.

Metric	What it tells you	Reference point	Source
Open rate	Subject line and sender appeal (unreliable since 2021)	21.33% average across industries	Mailchimp benchmarks, pre-2021 data
Click rate	Content relevance and call-to-action strength	2.62% average across industries	Mailchimp benchmarks, pre-2021 data
Unsubscribe rate	Frequency or relevance problems	0.26% average	Mailchimp benchmarks, pre-2021 data
Hard bounce rate	List quality (invalid addresses)	0.40% average	Mailchimp benchmarks, pre-2021 data
Spam complaint rate	Whether people want your mail	Under 0.1% target, 0.3% maximum	Google bulk sender guidelines

Why open rates lie now

In September 2021, Apple launched Mail Privacy Protection with iOS 15. When it’s turned on, Apple Mail preloads email content, including the tracking pixel, on Apple’s servers. Your ESP logs an “open” whether or not the person ever looked at the message.

The result: open rates jumped across the industry, and they no longer reliably reflect reading. The Mailchimp averages above predate that change, which makes them a useful baseline for how opens used to look but a poor target for today’s inflated numbers.

What to do about it:

• Judge campaigns by clicks, conversions and revenue, not opens.
• Don’t use opens alone to define “engaged” subscribers. Combine them with clicks and purchases.
• Be cautious with open-based A/B subject line tests, since Apple users skew the results.

Revenue per recipient

For ecommerce, revenue per recipient (total campaign revenue divided by emails delivered) is the single most useful number. It lets you compare a 5,000-person segment send with a 50,000-person blast fairly. A smaller, better-targeted campaign often earns more per email.

Inbox health signals

Set up Google Postmaster Tools for your domain. It shows your spam complaint rate, domain reputation and authentication pass rates for Gmail traffic. Microsoft offers Smart Network Data Services (SNDS) for IP-level data. Check both weekly once you’re sending regularly.

How Subscribers Treat Your Emails Once They Land

This angle rarely shows up in beginner guides, yet it drives inbox placement more than any subject line trick.

Mailbox providers watch what each user does with your messages. Opening, replying, moving an email from Promotions to Primary and adding you to contacts all count as positive signals. Deleting without reading, marking as spam and ignoring you for months count against you.

Inbox cleaning matters here. Plenty of people periodically wipe out thousands of unread promotions at once, and guides showing how to bulk delete Gmail emails are popular for a reason. If your messages are the ones getting cleared in bulk without ever being opened, Gmail notices the pattern over time.

You can counter this in a few ways:

• Ask for a reply in your welcome email. A question like “What’s the one thing you want help with?” earns replies, and replies are a strong positive signal.
• Send less to people who engage less. Many ESPs let you create a “sunset” segment that receives only your best campaigns.
• Make unsubscribing painless. Someone who can’t find the unsubscribe link will hit “Report spam” instead. A clean unsubscribe protects your reputation.
• Keep transactional and marketing streams separate. Many senders use a subdomain like mail.yourbrand.com for marketing, so a rough campaign doesn’t slow down order confirmations.

Before You Click Send: 10 Things to Check

Run through this list before every campaign. It takes five minutes and prevents most of the problems we see.

1. Authentication passes. SPF, DKIM and DMARC all show “pass” in a test message’s headers.
2. The audience is right. You’ve selected the correct segment and excluded unsubscribes, bounces and suppressed contacts.
3. Consent is real. Everyone on the list opted in or has a legitimate relationship under the law that applies.
4. The subject line is honest. It matches what’s inside.
5. The preheader is set. Otherwise, clients show the first line of body text, often “View in browser.”
6. Links work. Every one, including the logo and footer.
7. Personalization has fallbacks. “Hi there” instead of a blank or a raw merge tag.
8. The footer is complete. Physical postal address, unsubscribe link and a line explaining why they’re receiving the email.
9. It looks right on mobile. Check on an actual phone, not just the editor preview.
10. Send time fits the audience. Schedule by recipient time zone if your ESP supports it.

5 Email Marketing Practices You Should Never Forget

Strip email marketing down to its essentials, and these five practices remain.

1. Never buy, rent or scrape a list. Purchased lists contain spam traps and people who never consented. They break GDPR and CASL outright, and they’ll destroy your domain reputation within a few sends. Build your list slowly and legally.

2. Warm up a new domain gradually. Mailbox providers distrust sudden volume from unknown senders. Start by emailing your most engaged subscribers, then increase volume over several weeks.

3. Clean your list regularly. Remove hard bounces immediately (your ESP should do this automatically). Run a re-engagement series every few months, and remove people who don’t respond.

4. Keep a consistent schedule. Subscribers who expect your newsletter every Tuesday open it. Subscribers who hear from you twice in March and then nothing until November forget who you are and hit spam.

5. Give more than you ask. For every sales email, send something useful: a tip, a story, early access, a how-to. People stay subscribed to senders who make their inbox better.

Common Beginner Mistakes

A few errors show up again and again with new senders:

• Sending from a free Gmail or Yahoo address. It fails DMARC through any ESP. Use your own domain.
• Importing an old contact list into a new ESP and blasting it. Addresses from three years ago include dead accounts and people who’ve forgotten you. Expect bounces and complaints.
• Hiding the unsubscribe link. Tiny grey text on a grey background pushes people to the spam button instead.
• Only sending promotions. A list that hears “SALE” every week stops listening.
• Ignoring automation. A welcome series and abandoned cart flow take an afternoon to set up and keep working for years.
• Chasing open rates. Since Apple’s privacy change, opens mislead. Clicks and revenue tell the truth.

FAQ

Is email marketing still effective?

Yes. Email reaches more than four billion users worldwide, according to Radicati Group figures, and it remains one of the highest-ROI channels marketers use. It works best for businesses that send relevant, permission-based emails rather than mass blasts.

How much does email marketing cost?

You can start free. Several major ESPs have free plans for small lists, though limits change, so check current pricing. Paid plans scale with the number of contacts, so a list of a few thousand subscribers typically costs tens of dollars a month, not hundreds.

What’s the difference between email marketing and spam?

Permission. Email marketing goes to people who opted in, clearly identifies the sender and lets recipients unsubscribe easily. Spam is unsolicited bulk email, often with misleading headers or subject lines. Mailbox providers and spam laws treat the two very differently.

How often should I send marketing emails?

Most small businesses do well with one newsletter or campaign a week, plus automated emails triggered by customer actions. Watch your unsubscribe and complaint rates. If they climb after you increase frequency, scale back or let subscribers choose how often they hear from you.

Do I need my own domain for email marketing?

Yes. Gmail, Yahoo and Microsoft require bulk senders to authenticate with SPF, DKIM and DMARC, which you can only set up on a domain you control. Sending marketing email from a free webmail address through an ESP will fail authentication.

Can I email people who gave me their business card?

In the US, CAN-SPAM allows it as long as you include an opt-out and follow the other rules. In the EU, UK and Canada, a business card alone generally isn’t enough consent for marketing emails. The safest approach is to send one personal follow-up and invite them to subscribe.