# Gmail vs Outlook: which spam filter is better?

URL: https://iblockspam.com/blog/gmail-vs-outlook-spam-filter
Last updated: 2026-11-03
Published: 2026-11-03
Topic: Choosing a filter
Author: iBlockSpam Team

> Gmail vs Outlook spam filtering compared: who really filters your mail, where junk goes, how long it's kept, reporting and blocking, and how to get less spam.

## Short answer

Neither Google nor Microsoft publishes catch rates you can compare, so no honest test crowns a winner. Both filter on their servers: Gmail moves spam to a Spam folder, Outlook to Junk Email. The real differences are the user controls and the paid business add-ons, and the app you read mail in rarely changes the result.

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](https://workspace.google.com/intl/en/security/threat-prevention/)). 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](https://iblockspam.com/blog/why-do-i-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](https://support.microsoft.com/en-au/outlook/overview-of-the-junk-email-filter-in-classic-outlook)), so it does little unless you raise it. Our [Outlook junk email filter settings guide](https://iblockspam.com/blog/outlook-junk-email-filter-settings) 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.

| | Gmail | Outlook.com / Microsoft 365 |
|---|---|---|
| Where suspected spam goes | Spam folder | Junk Email folder |
| How long it's kept | Delete it yourself with Delete forever or Delete all spam messages now | Outlook.com: Microsoft pages say 10 to 30 days; Microsoft 365 default: 30 days |
| Report spam | Report spam | Report, then the junk option (labels vary by version) |
| Report phishing | More > Report phishing | Report > Report phishing |
| Block a sender | More > Block; future mail goes to Spam | Settings > Mail > Junk email > Blocked senders and domains |
| Always allow a sender | Add to contacts or create a filter | Settings > Mail > Junk email > Safe senders and domains |
| Filter strictness levels | None for users | Classic Outlook only: No Automatic Filtering, Low, High, Safe Lists Only |
| Extra link and attachment checks (consumer) | Warnings on suspicious messages for every account | Advanced scanning for Microsoft 365 Personal and Family subscribers |
| Business admin layer | Google Workspace Gmail settings and admin quarantine | Microsoft 365 anti-spam policies, quarantine, Defender for Office 365 |

Sources: [Gmail Help](https://support.google.com/mail/answer/1366858?hl=en), [Microsoft Support](https://support.microsoft.com/outlook/filter-junk-email-and-spam-in-outlook) 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](https://support.google.com/mail/answer/1366858?hl=en)).
- **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](https://support.google.com/mail/answer/8253?hl=en)).
- **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](https://support.google.com/mail/answer/8151?hl=en)). 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](https://support.microsoft.com/en-gb/office/how-to-deal-with-phishing-in-outlook-com-0d882ea5-eedc-4bed-aebc-079ffa1105a3)).
- **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](https://support.microsoft.com/outlook/filter-junk-email-and-spam-in-outlook)).
- **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](https://support.microsoft.com/en-us/office/mail-goes-to-the-junk-folder-by-mistake-f409b58c-2617-47e2-8a97-cab612d98eff)), another says junk email "is retained for 30 days before it is automatically deleted and is not recoverable" ([Microsoft Support](https://support.microsoft.com/outlook/filter-junk-email-and-spam-in-outlook)). For Microsoft 365 work mailboxes, the [Default MRM Policy](https://learn.microsoft.com/en-us/exchange/security-and-compliance/messaging-records-management/default-retention-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](https://iblockspam.com/blog/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](https://iblockspam.com/blog/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](https://support.microsoft.com/office/882d2243-eab9-4545-a58a-b36fee4a46e2)).

## 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](https://learn.microsoft.com/en-us/defender-office-365/recommended-settings-for-eop-and-office365)). See the [Microsoft 365 business plans comparison](https://iblockspam.com/blog/microsoft-365-business-plans-email-security-compared).
- **Google Workspace** gives every edition opt-in Safety settings, and adds Security Sandbox from Business Standard up. See the [Google Workspace editions comparison](https://iblockspam.com/blog/google-workspace-editions-email-security-compared).

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](https://iblockspam.com/blog/using-personal-gmail-for-business-risks). For a fuller side-by-side of the two business platforms, read [Google Workspace vs Microsoft 365 email security](https://iblockspam.com/blog/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:

```text
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](https://learn.microsoft.com/en-us/defender-office-365/message-headers-eop-mdo)). 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](https://iblockspam.com/blog/microsoft-365-spam-headers-explained) and [how to read email headers](https://iblockspam.com/blog/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](https://iblockspam.com/blog/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?](https://iblockspam.com/blog/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](https://iblockspam.com/blog/why-did-this-email-land-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](https://iblockspam.com/blog/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](https://iblockspam.com/blog/stop-spam-for-whole-domain).

Not sure a message is genuine? Open its headers in the free [Email Header Analyzer](https://iblockspam.com/tools/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](https://iblockspam.com/blog/how-to-choose-a-spam-filter-small-business) covers what to compare, and [iBlockSpam for small businesses](https://iblockspam.com/solutions/small-business) 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](https://iblockspam.com/tools/email-header-analyzer) before you click anything.
- If you manage email for a business, compare plan features in the [Microsoft 365](https://iblockspam.com/blog/microsoft-365-business-plans-email-security-compared) and [Google Workspace](https://iblockspam.com/blog/google-workspace-editions-email-security-compared) guides, and see how a filter in front works on our [small business page](https://iblockspam.com/solutions/small-business).

## Frequently asked questions

### If I read my Gmail account in the Outlook app, which spam filter applies?

Mostly Gmail's. Spam filtering happens on the mail provider's servers when a message arrives, so a Gmail account is filtered by Google wherever you read it. Classic Outlook for Windows also has its own client-side Junk Email Filter, but Microsoft sets it to No Automatic Filtering by default, so it adds little unless you raise the level.

### How long does Outlook keep messages in the Junk Email folder?

It depends on the account. Microsoft's consumer support pages give figures from 10 to 30 days for Outlook.com, so treat Junk as temporary. For Microsoft 365 work mailboxes, Exchange Online's Default MRM Policy deletes Junk Email items after 30 days, though an admin can change that tag.

### Does blocking a sender in Gmail stop their emails completely?

No. Google says that after you block a sender, all future emails from them go to Spam. They still arrive in your account and the sender isn't told. To stop a domain reaching anyone at all in a business, an admin needs a server-side block list or filter rather than a personal block.

### Does Outlook.com scan links and attachments for free users?

Free Outlook.com accounts get spam and malware filtering. Microsoft says the extra attachment scanning and Safelinks link checking are for Microsoft 365 Family and Personal subscribers using Outlook.com, Hotmail, Live or MSN addresses, and turn on automatically for them.

### Will switching from Outlook to Gmail reduce my spam?

Probably not by much. Your address is already on spam lists, and both providers filter the bulk of it. Switching also means a new address, migration and telling every contact. Reporting spam, unsubscribing from legitimate senders and keeping your address off public web pages usually make a bigger difference.

## Sources

- [Google Workspace: Threat prevention (Gmail protection claims)](https://workspace.google.com/intl/en/security/threat-prevention/)
- [Gmail Help: Mark or unmark spam in Gmail](https://support.google.com/mail/answer/1366858?hl=en)
- [Gmail Help: Block or unsubscribe from emails](https://support.google.com/mail/answer/8151?hl=en)
- [Microsoft Support: Filter junk email and spam in Outlook](https://support.microsoft.com/outlook/filter-junk-email-and-spam-in-outlook)
- [Microsoft Support: Mail goes to the Junk folder by mistake](https://support.microsoft.com/en-us/office/mail-goes-to-the-junk-folder-by-mistake-f409b58c-2617-47e2-8a97-cab612d98eff)
- [Microsoft Support: Advanced Outlook.com security for Microsoft 365 subscribers](https://support.microsoft.com/office/882d2243-eab9-4545-a58a-b36fee4a46e2)
- [Microsoft Learn: Default Retention Policy in Exchange Online](https://learn.microsoft.com/en-us/exchange/security-and-compliance/messaging-records-management/default-retention-policy)
- [Microsoft Support: Overview of the Junk Email Filter in classic Outlook](https://support.microsoft.com/en-au/outlook/overview-of-the-junk-email-filter-in-classic-outlook)

## Free tools for this guide

- [Email Header Analyzer](https://iblockspam.com/tools/email-header-analyzer): Trace hops and authentication results — runs entirely in your browser.
- [Email Deliverability Test](https://iblockspam.com/tools/deliverability-test): Send one email and see its SPF, DKIM and DMARC results, reverse DNS, blocklists, TLS and spam verdict.
- [DMARC Checker](https://iblockspam.com/tools/dmarc-checker): Check your policy, reporting and the safe path from p=none to reject.
- [Email Health Check](https://iblockspam.com/tools/email-health-check): Grade your domain's MX, SPF, DKIM, DMARC and transport security in one scan.

---

Source: iBlockSpam, https://iblockspam.com/blog/gmail-vs-outlook-spam-filter (this is a Markdown copy; the HTML page is canonical). Quote with attribution and a link. Site index for AI assistants: https://iblockspam.com/llms.txt