Gmail vs Outlook: which spam filter is better?

People ask whether Gmail or Outlook blocks more spam as if it were a simple contest. It isn't, because the spam filter belongs to your email provider, not to the app on your screen, and neither provider publishes numbers that let you compare them. This guide explains who actually filters your mail, compares what Gmail and Outlook let you do about spam, and lists the steps that make a real difference on either one. Menus are as documented at the time of writing (November 2026).

Is Gmail or Outlook better at filtering spam?

There's no reliable answer, because neither company publishes catch rates measured the same way and no independent body tests them head to head. Google says "more than 99.9% of spam, phishing attempts, and malware are automatically blocked in Gmail" (Google Workspace). That's Google's own figure, on a marketing page, with no published method. Microsoft doesn't publish an equivalent percentage for Outlook.com.

The comparisons you find online are mostly anecdotes or vendor blogs. Some say Gmail lets less through. Others prefer Outlook. Both kinds of claims depend on which addresses the writer had, how long they'd had them, and what lists those addresses were on. Your own experience is a better guide: if one account gets much more spam, the address is usually the reason, not the filter. Our guide to why you get so much spam explains how addresses end up on lists.

What you can compare fairly is how each service handles spam and what each lets you control. That's the rest of this guide.

Does the email app or the email provider filter spam?

The email provider filters spam, on its servers, before the message reaches any app. A Gmail account is filtered by Google whether you read it in the Gmail app, Apple Mail or Outlook. An Outlook.com or Microsoft 365 account is filtered by Microsoft whether you read it in Outlook, the Gmail app or a phone's built-in mail app.

This matters because "Gmail vs Outlook" can mean three different things:

1. The free consumer services: a gmail.com address against an outlook.com or hotmail.com address.
2. The business services: Google Workspace against Microsoft 365, where admins add policies on top of the default filter.
3. The apps: the Gmail app against the Outlook app. Apps mostly just show what the server already decided.

There's one exception. Classic Outlook for Windows has its own client-side Junk Email Filter. Microsoft says that by default "the protection level is set to No Automatic Filtering" (Microsoft Support), so it does little unless you raise it. Our Outlook junk email filter settings guide explains the levels and why Microsoft recommends leaving Microsoft 365 mailboxes at No Automatic Filtering.

How do Gmail and Outlook compare side by side?

The table compares the consumer services and notes where business accounts differ.

Sources: Gmail Help, Microsoft Support and the pages linked below.

How does Gmail's spam filter work for users?

Gmail moves suspected spam to the Spam folder and shows warnings on messages it finds suspicious, such as spoofed senders or likely phishing. You train it by reporting mistakes in both directions.

• Report spam: select one or more emails and click Report spam. Google says "as you report more spam, Gmail identifies similar emails as spam more efficiently" (Gmail Help).
• Not spam: open Spam, select the message and click Not spam.
• Report phishing: open the message, click More (three dots) next to Reply, then Report phishing (Gmail Help).
• Block: open a message, click More, then Block. Google says "after you block the sender, all future emails from them go to Spam" (Gmail Help). Manage blocks under Settings > See all settings > Filters and Blocked Addresses.
• Filters: search for a sender or phrase, then choose Create filter to label, archive, delete or forward matching mail.

Gmail gives users no strictness setting. If too much gets through, reporting and filters are your tools. Google's consumer Spam folder empties itself over time, but Google's help pages that we checked don't state the exact period, so don't keep anything there you need.

How does Outlook's junk filter work for users?

Outlook moves suspected spam to the Junk Email folder. In Outlook.com, Outlook on the web and new Outlook, you manage it in Settings > Mail > Junk email.

• Report junk or phishing: select the message, then Report above the reading pane and choose the junk option or Report phishing. Older versions label this menu Junk, so the wording varies. Microsoft notes that reporting phishing reports the sender but "is not blocked from sending you additional messages" (Microsoft Support).
• Block: Blocked senders and domains > Add blocked sender. You can enter a whole domain.
• Allow: Safe senders and domains > Add safe sender. Microsoft says messages from addresses or domains on that list "won't get moved to your Junk Email folder" (Microsoft Support).
• Fix a mistake: in Junk Email, select the message and choose It's not junk.

How long Junk keeps mail depends on the account. Microsoft's own consumer pages disagree: one says messages "are automatically deleted between 10 and 30 days after they arrive" (Microsoft Support), another says junk email "is retained for 30 days before it is automatically deleted and is not recoverable" (Microsoft Support). For Microsoft 365 work mailboxes, the Default MRM Policy has a Junk Email tag of 30 days with "Delete and Allow Recovery". Either way, check Junk weekly.

Don't confuse Junk Email with Focused Inbox. The Other tab only sorts mail you're less likely to read; it isn't a spam verdict. See Outlook Focused Inbox vs Junk Email. Outlook may also show a question mark on a sender it couldn't verify, which our guide to the Outlook unverified sender question mark explains.

Outlook.com has one paid extra. Microsoft says Microsoft 365 Family and Personal subscribers get advanced attachment scanning and Safelinks link checking on Outlook.com, Hotmail, Live and MSN addresses, while free users get "spam and malware filtering" (Microsoft Support).

What changes for business accounts?

For business email, the comparison is really Google Workspace against Microsoft 365, and the admin settings matter more than the default filter. Both filter every mailbox. Both let admins quarantine mail, block senders for the whole company and add stronger protection in higher plans.

The main differences are where the stronger protection sits:

• Microsoft 365 puts link checks at the time of click, attachment sandboxing and impersonation protection in Defender for Office 365, included in Business Premium and, since July 1, 2026, in Office 365 E3 and Microsoft 365 E3. In Microsoft's default anti-spam policy, spam, bulk mail and ordinary phishing go to Junk Email, and high confidence phishing goes to quarantine (Microsoft Learn). See the Microsoft 365 business plans comparison.
• Google Workspace gives every edition opt-in Safety settings, and adds Security Sandbox from Business Standard up. See the Google Workspace editions comparison.

If you run a business from a free gmail.com or outlook.com address, you get none of the admin controls; see the risks of using personal Gmail for business. For a fuller side-by-side of the two business platforms, read Google Workspace vs Microsoft 365 email security.

How can you see why a message was marked as spam?

The message headers record the filter's evidence, and both providers write the same standard field for authentication. Open the original message (in Gmail, More > Show original; in Outlook, view the message source or headers) and look for Authentication-Results. A trimmed example, with made-up domains:

Authentication-Results: mx.example.net;
  spf=pass smtp.mailfrom=news.example.com;
  dkim=pass header.d=example.com;
  dmarc=pass header.from=example.com

If SPF, DKIM and DMARC pass, the sender is who it says it is, which tells you the message is authentic but not that it's wanted. If DMARC fails on a message claiming to be your bank, treat it as phishing.

Microsoft adds its own verdict on top. Its X-Forefront-Antispam-Report header carries fields such as SFV:SPM, which Microsoft says means "the message was marked as spam by spam filtering", and CAT, the category of policy that acted, such as SPM for spam or PHSH for phishing (Microsoft Learn). Microsoft also says the old SCL number "doesn't determine whether the message is identified as spam" in cloud mailboxes, so read SFV and CAT instead. Gmail doesn't publish an equivalent verdict field, so for Gmail the authentication results and Gmail's own warning banner are what you have. Our guides to Microsoft 365 spam headers and how to read email headers go further.

Why does spam still get through either filter?

Some spam reaches the inbox on both services, for the same reasons:

• It comes from real accounts. A message sent from a genuine free Gmail or Outlook.com account passes SPF, DKIM and DMARC, so authentication checks don't flag it. See display name spoofing.
• It's new. A fresh domain or a new campaign has no bad history yet. Filters catch up as people report it.
• It's legitimate bulk mail. Newsletters you once signed up for are "graymail", not spam. Unsubscribing works better than reporting; see is it safe to unsubscribe from spam?.
• Your rules let it in. A safe sender entry, contact or filter can override the spam decision.

Our guide to why an email landed in spam works in the other direction, for good mail that was caught.

How do you get less spam in Gmail or Outlook?

The same checklist works on both:

1. Report, don't just delete. Use Report spam in Gmail or the Report menu's junk option in Outlook, so the filter learns.
2. Report phishing separately. Phishing reports go to a different process from spam reports on both services.
3. Unsubscribe from senders you recognize. Use the unsubscribe link only for real companies you once dealt with.
4. Block repeat senders, remembering that blocked mail still arrives in Spam or Junk.
5. Clean up your allow rules. Remove safe senders, contacts and filters you no longer need.
6. Stop publishing your address. See protect public email addresses from spam.
7. For a business, filter before the mailbox. Admins can set company-wide policies or add a gateway; see how to stop spam for a whole domain.

Not sure a message is genuine? Open its headers in the free Email Header Analyzer, which runs in your browser, to see whether it passed SPF, DKIM and DMARC.

Should you switch from Outlook to Gmail, or back, to get less spam?

Usually not. Switching providers changes your address, which does cut spam at first, simply because the new address isn't on any lists yet. Most of that benefit comes from the new address, not the new filter, and it fades as the address spreads. You also pay for it with a migration and a long period of telling contacts.

If you run a business on your own domain, you can change the filter without changing anyone's address. An MX-level filtering service sits in front of Microsoft 365 or Google Workspace and filters mail before your provider sees it, with a personal quarantine digest for each user. Our guide on how to choose a spam filter for a small business covers what to compare, and iBlockSpam for small businesses explains how ours works.

Next steps

• Decide which question you're asking: consumer accounts, business platforms or apps. Only the first two change the filter.
• Spend a week reporting every spam message instead of deleting it, on whichever service you use.
• Check a suspicious message with the Email Header Analyzer before you click anything.
• If you manage email for a business, compare plan features in the Microsoft 365 and Google Workspace guides, and see how a filter in front works on our small business page.