How to Block an Entire Email Domain in Outlook.com

If a company keeps emailing you from different addresses — sales@, noreply@, info@ — blocking one sender at a time solves nothing. Outlook.com's Blocked Senders list lets you block by domain, so that every message from that domain goes to Junk regardless of which address it came from.

This guide covers exactly how to block an email domain in Outlook.com, what happens to blocked mail, where the method breaks down, and how an inbox rule closes the gap when a sender rotates through subdomains.

The short answer#

Yes, you can block an entire domain in Outlook.com. Open Settings, go to Mail then Junk email, and add the domain to the Blocked senders and domains list. You can enter it as example.com or @example.com — both formats are accepted and stored identically. Mail from that domain starts landing in Junk immediately after you save.

Three things to know before you start. Blocked mail is permanently deleted from Junk after 14 days with no recovery option — this is not the same as archiving. The Blocked Senders and Safe Senders lists share a single combined cap of 10,000 entries. And blocking example.com does not block mail from promo.example.com — subdomains require a different step, covered in the troubleshooting section below.

Before you start: account and app restrictions#

The Blocked Senders list is a feature of Outlook.com — Microsoft-hosted addresses at @outlook.com, @hotmail.com, @live.com, and related domains. If you are using Outlook as the app for a Gmail, Yahoo, or other third-party address, the situation is different.

• Outlook.com accounts on the web (outlook.com, hotmail.com, live.com): full domain blocking available — follow the steps below.
• New Outlook for Windows with a Microsoft account: supported; manage the blocked list at outlook.com in a browser.
• New Outlook for Windows with a Gmail, Yahoo, or IMAP account: not supported in the app; configure blocking through your original email provider.
• Outlook mobile (iOS and Android): individual address blocking only in the app; domain blocks must be set from outlook.com on the web.
• Microsoft 365 or Exchange accounts managed by an IT admin: tenant-level domain blocking is in the Microsoft Defender portal, and your Junk email settings may be controlled by policy.

How to block an email domain in Outlook.com#

1. 1

   Open Settings

   Sign in at outlook.com and click the gear icon in the top-right corner. At the bottom of the settings panel, select View all Outlook settings to open the full settings page.

2. 2

   Go to Junk email

   In the settings sidebar, select Mail, then Junk email. The Blocked senders and domains list appears at the top of the page.

3. 3

   Add the domain

   Click Add and type the domain you want to block — for example, spammysender.com. You can also enter it as @spammysender.com; Outlook treats both formats identically. Press Enter or click the checkmark to confirm the entry.

4. 4

   Save

   Click Save at the bottom of the page. Outlook begins routing mail from that domain to your Junk Email folder immediately. Each domain you add counts as one entry toward the 10,000-entry cap shared with your Safe Senders list.

Where domain blocking is and isn't available#

Outlook reaches across desktop, web, and mobile, but not every surface exposes the same settings. Use this table to confirm what is available for your setup before spending time looking for a setting that is not there.

What to do when blocked mail still gets through#

The most common reason a domain block stops working is subdomains. When you add example.com to the blocked list, Outlook filters mail from addresses @example.com — but not from @promo.example.com, @b1.example.com, or @mail.example.com. Each subdomain is treated as a completely separate domain, and the block on the root domain does not extend to them.

Bulk senders and spam operations rely on this behaviour. A sender blocked at the root domain can keep reaching your inbox simply by switching to a new subdomain. Adding each one by hand is a loop that never ends, because generating a new subdomain costs the sender nothing.

The fix is an inbox rule using the Sender address includes condition. Unlike the blocked list — which must match the exact domain string — this condition performs a substring match on the full sender address. Entering example.com as the match string catches mail from @example.com, @promo.example.com, @b1.example.com, and any other variant, because all of them contain the string example.com somewhere in the address.

Setting up an inbox rule to block a domain including subdomains#

1. 1

   Open Rules settings

   In outlook.com, go to Settings, then Mail, then Rules. Click Add new rule. Give the rule a name you will recognise — for example, Block spammysender and all subdomains.

2. 2

   Set the condition

   Under Add a condition, select Sender address includes from the dropdown. In the text field, type the parent domain — for example, spammysender.com. Do not include the @ sign; you want a substring match, not an exact address match.

3. 3

   Choose an action

   Under Add an action, select Delete to discard matching messages immediately, or select Move to and choose Junk Email if you want to review them before the 14-day automatic deletion window closes.

4. 4

   Add an exception for senders you still want

   Click Add an exception and select From. Enter any specific addresses from that domain that should still reach your inbox — for example, a newsletter you subscribed to. Exceptions are evaluated after the condition, so those addresses will skip the rule.

5. 5

   Save and verify

   Click Save. The rule applies to new incoming mail immediately. You can edit or delete it at any time from the Rules settings page. If you want to test it, send a message from an external address at that domain, or wait for the next one from that sender.

A faster way to keep unwanted domains out of your inbox#

The steps above work, but they require attention every time a new sender domain or subdomain appears. The 10,000-entry cap also means a heavily-filtered inbox will eventually run out of room on the blocked list.

We build AI Emaily, an AI email client that connects to Outlook, Gmail, and IMAP accounts. Its cold-email filter matches on sender behaviour and domain patterns rather than a static list — so a bulk sender rotating through subdomains does not reset the filter each time it switches to a new one. Mail that fits the pattern is routed out of the primary inbox automatically, with no list to maintain and no entry cap to hit. Anything the filter catches can be reviewed, and individual senders can be marked safe with one click. If managing the blocked list is taking time you would rather not spend, you can start at app.aiemaily.com.