How to Block Someone on Outlook (And What It Doesn't Do)

In new Outlook and Outlook on the web, go to Settings > Mail > Junk email, type the address into the Blocked senders box, select Add, then select Save. Microsoft's documentation says mail from a blocked address is then moved automatically to your Junk Email folder instead of your inbox.

Most people searching for how to block someone on Outlook want one narrow thing: that person's email out of the inbox, without a conversation about it. Outlook will do that. It is just quieter and more limited than the word "block" suggests.

Two things are worth knowing before you change anything. Blocking filters mail, it does not sever the account — the messages still arrive, they just land somewhere else. And if the address you want to block belongs to a Gmail or iCloud account you added to Outlook rather than a Microsoft one, the setting will not work at all.

Where the blocked senders list lives

This is the route that works whether or not you still have a message from the person in front of you. It is the same in new Outlook for Windows and in Outlook on the web.

1. If you have more than one account in Outlook, select the account you want to change. The blocked list belongs to a single mailbox, not to the app.

2. Go to Settings > Mail > Junk email. The Settings gear sits at the top right of the window.

3. Type the address into the Blocked senders box and select Add. To block every address at a domain instead, put the domain into Blocked domains and select Add there.

4. Select Save. Nothing takes effect until you do.

Microsoft sets a combined ceiling of 10,000 addresses and domains across your blocked and safe senders lists, and suggests blocking whole domains rather than individual addresses if you are getting close to it. For one difficult sender, that ceiling will never matter.

Block someone on Outlook straight from the message

If the email is already open in front of you, you do not need the settings page at all.

Right-click the message, hover over Block, then choose Block sender and confirm. You can also open the message, select the three-dot More options menu at the top right, and take Block from there. Either way the address is added to the same list you would otherwise have edited by hand.

Guides disagree on what happens to the message you were looking at when you did it — some describe it moving to Junk, others to Deleted Items. The behaviour for future messages is the consistent part: those go to Junk.

Classic Outlook and the mobile app

Classic Outlook for Windows, the version with the older ribbon, uses different wording for the same idea. Right-click the message and choose Junk > Block Sender, or use Home > Junk > Block Sender on the ribbon. To see the list itself, go to Home > Junk > Junk E-mail Options and open the Blocked Senders tab, where entries can also be imported and exported.

Classic Outlook's allowance is tighter than the new app's. On an Exchange account the Blocked Senders, Safe Senders and Safe Recipients lists share a limit of roughly 1,024 entries between them.

In the Outlook mobile app, open a message from the sender, tap the three-dot menu at the top right, and take Block sender or Move to Junk. The phone app is thinner here: there is no blocked senders list to review on the device, so to audit or undo anything you will still end up in the web version.

What this does not do

This is where most of the confusion sits, and it is the reason blocking sometimes feels like it has not worked.

It does not delete mail that already arrived. Blocking only changes where new messages go. Anything already sitting in your inbox stays there until you move it yourself.

It does not close every door. Microsoft notes that a blocked account will not appear in Teams people-picking or search unless you have already interacted with that person in Teams — but someone who types your full email address can still reach you there, subject to your organisation's policies.

It does not work on non-Microsoft accounts. Microsoft states that new Outlook does not support blocking senders on third-party accounts such as Gmail, Yahoo or iCloud added to the app. For those you have to use that provider's own settings instead.

It does not unsend anything. If what you actually want is to pull back a message you already sent to that person, that is a different feature with its own narrow conditions — see how to recall an email in Outlook.

Common questions

Does the person know they have been blocked? Microsoft's documentation on blocked senders does not describe any notification being sent, and does not describe a bounce message going back to them either. Community answers on Microsoft's own forums say no notice is sent, but that is not confirmed in the documentation, so it is better treated as likely than as certain.

How long does blocked mail stick around? Microsoft's pages disagree. The blocked senders page says Junk Email is removed after 14 days; the junk filtering page says 30. Either way it clears itself and cannot be recovered afterwards, so check Junk before the clock runs out if you are blocking someone you may later need a record from.

Should I block, or write a rule? Blocking is one list with one outcome. A rule can file, forward, flag or delete based on conditions you choose, and is the better tool if you want the mail kept but out of sight. Outlook's other inbox controls, such as setting up an automatic reply, are separate again.

If the option isn't there

There are two common reasons. The Block option is reported as unavailable on some non-Exchange account types, which lines up with Microsoft's note about third-party accounts. And if you are trying to block from inside the Junk folder, the option can simply be missing — move the message back to the inbox first, then block it from there.

If neither applies and the setting still will not hold, check that you picked the right account at step 1 and that you actually pressed Save. Failing that, editing the list by hand in the web version is the most reliable route, and changes made there apply to the same mailbox you use on the desktop.