Microsoft’s Hotmail Update: Sweep, Graymail Filtering and Trusted Senders

Hotmail no longer exists as its own service. Microsoft moved every Hotmail account to Outlook.com between July 2012 and May 2013. Sweep, the 2010 feature that worried email marketers, is still in Outlook.com today, and Focused Inbox now sorts newsletters into an “Other” tab. The biggest change since this post was written was announced by Microsoft on April 2, 2025, with enforcement beginning May 5, 2025: domains that send more than 5,000 emails a day to Outlook.com consumer services, including Hotmail.com and Live.com addresses, must pass SPF, DKIM and DMARC, with DMARC set to at least p=none. Mail that fails can be rejected with error 550 5.7.515.

What the 2010 Hotmail update introduced

In 2010, Microsoft launched a redesigned Hotmail (known as “Wave 4”) with new features to cut inbox clutter and pull in social media. These were the main changes:

Hotmail Highlights: A dashboard that grouped email from your contacts, social networking sites, flagged messages and upcoming events you had marked. In practice these were built-in filters that worked from day one. It was a well-built feature.

Filters: Filter tabs that sorted inbox messages on the fly, based on each filter’s criteria.

Categories and Quick Views: Folders for Photos, Shipping Info and Documents. Hotmail sorted the most common types of email into them automatically, based on what each message contained.

Sweep: The most important change for marketers. Sweep let users clear unwanted mail out of the main inbox in a few clicks. Because of it, campaigns sent to Hotmail users risked getting less attention.

Trusted Senders: Hotmail put a small trust logo next to the subject line of mail it considered legitimate. People often compared it to Goodmail’s certified email icon. The two worked very differently, though. Goodmail was a paid certification service, while Trusted Senders started with about 100 frequently phished senders, such as banks, and relied on authentication and sending history. Goodmail shut down in February 2011, so the comparison is history now.

Hotmail’s spam handling also changed. Microsoft’s SmartScreen filtering separated “graymail” from real spam. Graymail means legitimate mail you signed up for, sometimes without noticing, such as newsletters, deals and social notifications. Microsoft later extended SmartScreen to pick out newsletters in particular, and said about half of all graymail came as newsletters.

At the time, many of these features looked too late to win over Gmail users. Taken together, though, the new Hotmail showed that email was becoming the hub for social communication online. One concern was that Hotmail’s audience, which skewed older and spent less time online, might not take to such big changes. Still, it was a step forward, not two steps back like Outlook 2007. That version swapped Internet Explorer’s HTML rendering for Microsoft Word’s engine, which broke many email designs. This is history now, though the Word engine still affects some desktop Outlook versions.

Microsoft’s preview page listed more features, including Office Web Apps and SkyDrive cloud storage. SkyDrive has since become OneDrive. The update moved Microsoft’s webmail in the right direction, and Outlook.com later replaced Hotmail completely.

Did Sweep sweep campaigns away

The 2010 question was whether Hotmail users would sweep marketing email away and never open it. Sixteen years later, Sweep and its successors do affect mail that people don’t want, but they don’t wipe out a whole channel. Sweep in Outlook.com and Outlook on the web lets a user:

1. Move or delete every message from one sender.
2. Block future messages from that sender, or move them automatically.
3. Keep only the latest message from that sender.
4. Delete that sender’s messages after 10 days.

By default, swept mail goes to Deleted Items. Users manage their saved Sweep rules under Settings > Mail > Sweep. Sweep runs in Microsoft’s cloud, so it only works on Microsoft-hosted mailboxes, not on IMAP or POP accounts.

For a sender, a Sweep rule works like a quiet unsubscribe. Your send counts as delivered, but nobody reads it. Watch for that pattern. Among Outlook.com recipients, a falling share of clicks while bounce rates stay flat often means people are sweeping your mail, not unsubscribing.

Focused Inbox makes this worse for weak programs. It splits the inbox into Focused and Other tabs, and users switch it on under Settings > Mail > Layout. Most bulk marketing lands in Other unless people engage with it. If a recipient moves your message to Focused, Outlook learns from that choice.

What Outlook.com expects from senders now

Microsoft’s high-volume sender rules match the bulk sender rules that Gmail and Yahoo started enforcing in February 2024. Most authentication work you do for one provider covers the others.

At its simplest, a DMARC record that meets the minimum looks like this:

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

Being on a recipient’s Safe Senders list doesn’t exempt you from this authentication check, which is the main difference from the old Trusted Senders badge. Today, trust comes from passing authentication on your own domain, not from a logo.

FAQ

Is Hotmail still a separate email service?

No. Microsoft began moving users to Outlook.com in July 2012 and finished upgrading every Hotmail account in May 2013. Hotmail.com addresses still work, but they run on Outlook.com, with the same filtering, Sweep and Focused Inbox.

Does Outlook.com’s Sweep feature count as an unsubscribe?

No. A Sweep rule only runs inside the recipient’s mailbox. Your platform doesn’t receive an unsubscribe, so you keep sending to someone who never sees your mail. A clear, one-click unsubscribe link is the better outcome for both sides, because an unread address drags down your engagement data.

What does error 550 5.7.515 mean?

Outlook.com rejected your message because the sending domain doesn’t meet Microsoft’s required authentication level for high-volume senders. Check that SPF authorizes your sending service, that DKIM signs with your own domain, and that a DMARC record exists and passes with alignment. Forwarded mail can also trigger the error when SPF breaks along the way.

How do I get out of the Other tab in Focused Inbox?

You can’t force your way into Focused. Outlook decides from how each recipient interacts with your mail. Send content that people open, reply to and move to Focused. Remove long-term non-openers, because sending to people who ignore you trains the filter against you.

Are open rates from Outlook.com still reliable?

Not fully. Apple Mail Privacy Protection, launched with iOS 15 in 2021, preloads images for many Apple Mail users, including those who read Outlook.com mail in Apple’s app. That inflates open rates. Clicks, conversions and complaint rates show more reliably whether Microsoft’s filters and your readers welcome your mail.

Do CAN-SPAM rules still apply to email sent to Outlook.com users?

Yes. Under the FTC’s CAN-SPAM rules, commercial email to US recipients needs accurate header information, a non-deceptive subject line, a valid postal address and a working opt-out that you honor within 10 business days. Mailbox provider rules come on top of the law and don’t replace it.

Sources

• Organize your inbox with Archive, Sweep, and other tools in Outlook on the web (Microsoft Support)
• Focused Inbox for Outlook (Microsoft Support)
• Fix NDR error 550 5.7.515 in Outlook.com (Microsoft Support)
• Outlook.com Postmaster: Policies, Practices, and Guidelines (Microsoft)
• Email sender guidelines (Google Workspace Admin Help)
• Sender Best Practices (Yahoo Sender Hub)
• CAN-SPAM Act: A Compliance Guide for Business (FTC)