Block a sender in Outlook on the web

Open the email from the sender you want to block. Click the three dots (more actions) in the top right of the message. Select Block from the menu. Outlook will move that sender's future emails to your Junk folder automatically.

If you want to remove the block later, go to Settings (the gear icon), then Mail > Junk email. Find the sender's address under "Blocked senders" and click the X next to their name to unblock them.

Block a sender in Outlook desktop app

Right-click the email from the sender you want to block. Select Junk > Block Sender. The sender will be added to your blocked list, and their future emails go straight to Junk.

To unblock someone, go to Home > Junk > Junk Email Options. Click the Blocked Senders tab. Find the sender and click Remove.

Key Takeaways

  • Blocking a sender in Outlook routes their future emails to your Junk folder instead of your inbox.
  • On the web, use the three-dot menu and select Block; in the desktop app, right-click and choose Junk > Block Sender.
  • You can unblock a sender anytime through Junk Email Options or Settings, depending on which version you use.
  • Blocking only affects new emails from that sender — it does not delete messages already in your inbox.
  • If a sender uses multiple email addresses, you will need to block each address separately.

What happens when you block someone

Once you block a sender, Outlook automatically sends their emails to your Junk folder. You will not see a notification when they send you a message. The emails stay in Junk for 10 days before Outlook deletes them permanently, unless you change your Junk settings.

Blocking does not delete emails that sender already sent you — those remain in your inbox unless you delete them manually. If you want to clean up old messages from that sender, search for their email address and delete the conversation yourself.

Block a sender by domain instead of individual address

If you are getting spam from many addresses at the same company or domain, blocking each one individually takes time. Instead, block the entire domain. In Outlook on the web, go to Settings > Mail > Junk email and scroll to "Blocked senders and domains." Type the domain name (for example, spammer.com) and click Add.

In the desktop app, go to Home > Junk > Junk Email Options > Blocked Senders. Type the domain name and click Add. All emails from any address at that domain will now go to Junk.

When blocking is not enough

If a sender keeps using new email addresses to get around your block, blocking individual addresses or domains will not stop them. In that case, create a rule to catch emails by subject line or content instead. In Outlook on the web, go to Settings > Mail > Rules and create a new rule that moves messages containing specific words to Junk.

In the desktop app, go to Home > Rules > Create Rule. Set conditions based on the sender's name, subject line, or message content, then choose to move matching emails to Junk. This catches variations of the sender's address that a simple block would miss.

Difference between blocking and unsubscribing

Blocking sends a sender's emails to Junk, but it does not tell them to stop sending. Unsubscribing is different — it removes you from a mailing list and signals to the sender that you no longer want their messages. Most legitimate newsletters and marketing emails have an unsubscribe link at the bottom.

Use unsubscribe for emails you signed up for but no longer want. Use block for unsolicited emails, spam, or senders you do not recognize. If an email does not have an unsubscribe link and you did not sign up for it, blocking is the right choice.

Frequently Asked Questions

Can I block someone without opening their email?

Yes. In Outlook on the web, right-click the email in your inbox list and select Block. In the desktop app, right-click the message and choose Junk > Block Sender. You do not need to open it first.

Will the sender know I blocked them?

No. Outlook does not send a notification to the sender. They will not receive a bounce-back message or any indication that you blocked them. Their emails simply go to Junk instead of your inbox.

What if I blocked someone by mistake?

Go to your Junk Email settings and find the sender in your blocked list. Click the X next to their name (web) or select them and click Remove (desktop app). Their future emails will go back to your inbox normally. Old emails in Junk stay there unless you move them.

Can I block emails from a specific subject line?

Blocking works on sender addresses only, not subject lines. If you want to block emails with a specific subject, create a rule instead. In Settings > Mail > Rules (web) or Home > Rules (desktop), set up a rule that moves messages with that subject to Junk automatically.

Does blocking work on mobile Outlook?

Yes. In the Outlook mobile app, swipe left on an email (iOS) or long-press it (Android), then tap the trash or block icon. The sender will be added to your blocked list on all devices where you use Outlook with the same account.