How to Block Someone on Outlook: A Complete Guide
Blocking unwanted senders in Outlook is one of those features that sounds simple but works differently depending on which version of Outlook you're using, what type of email account is connected, and whether you want a hard block or a softer filtering approach. Here's what you need to know.
What "Blocking" Actually Does in Outlook
When you block a sender in Outlook, you're not preventing them from sending you an email — their messages still arrive at Microsoft's servers. What happens is that Outlook automatically moves any incoming email from that address directly to your Junk Email folder, where it sits unread until you delete it or it expires.
This is an important distinction. Blocking in Outlook is a routing rule, not a firewall. The sender has no idea they've been blocked — they won't get a bounce-back or error message. Their emails just silently disappear into your junk folder.
How to Block Someone in Outlook on the Web (Outlook.com)
If you use Outlook through a browser at outlook.com or as part of Microsoft 365:
- Open the email from the sender you want to block
- Click the three-dot menu (⋯) in the top-right corner of the message
- Select "Block" → "Block sender"
- Confirm by clicking Block in the popup
That sender's address is now added to your Blocked Senders list, and future messages from them go straight to Junk.
You can also manage this list manually by going to Settings → Mail → Junk email → Blocked senders and domains.
How to Block Someone in Outlook Desktop App (Windows)
The desktop version of Outlook (part of Microsoft 365 or standalone Office) works slightly differently:
- Right-click the email from the sender you want to block
- Hover over "Junk"
- Select "Block Sender"
Outlook will move the current message to Junk and add that address to your Blocked Senders list. You can review or edit this list under Home → Junk → Junk Email Options → Blocked Senders tab.
How to Block Someone in the Outlook Mobile App 📱
On iOS or Android using the Outlook mobile app:
- Open the email from the sender
- Tap the three-dot menu in the top-right corner
- Select "Block Sender"
The experience is consistent across both platforms, though the exact menu layout may vary slightly depending on your app version.
Blocked Senders vs. Junk Email Filters: What's the Difference?
Outlook gives you two overlapping tools for managing unwanted mail, and they behave differently:
| Feature | Blocked Senders List | Junk Email Filter |
|---|---|---|
| How it works | Manually added addresses/domains | Automatic, AI-based filtering |
| What triggers it | Exact address or domain match | Content, sender reputation, patterns |
| Where mail goes | Junk Email folder | Junk Email folder |
| User control | Full manual control | Low/High/Exclusive settings |
| Best for | Known, specific senders | Unknown or bulk spam |
If you're dealing with a specific person or address, the Blocked Senders list gives you precise control. If you're trying to reduce spam broadly, adjusting the Junk Email Filter level under Junk Email Options is the more effective lever.
Blocking an Entire Domain
If you're receiving unwanted emails from multiple addresses at the same organization or domain (e.g., everything from @spamsite.com), Outlook lets you block the entire domain rather than individual addresses.
In the desktop app, go to Junk → Junk Email Options → Blocked Senders, click Add, and type the domain with an @ symbol (e.g., @example.com). In Outlook on the web, go to Settings → Junk email → Blocked senders and domains and add the domain directly.
Be careful with this approach — blocking a broad domain can accidentally filter out legitimate emails if the domain is used by multiple senders or services.
What Happens to Already-Received Emails?
Blocking a sender going forward doesn't retroactively move their previous emails. Messages already sitting in your inbox stay there. You'd need to manually delete or move those if needed.
Also worth knowing: if you mark a message as "Not Junk" from a blocked sender, Outlook may re-add them to your safe senders list depending on your settings — effectively undoing the block.
Variables That Affect How This Works for You
The blocking feature itself is consistent, but your experience will vary based on a few factors:
- Account type: Microsoft/Outlook.com accounts have full blocking functionality. If Outlook is connected to a Gmail, Yahoo, or other IMAP account, the blocked senders list may behave differently or not sync with the provider's own spam filters.
- Exchange/work accounts: In corporate environments managed by an IT department, your admin controls certain junk email settings and may restrict what you can add to blocked senders lists.
- Outlook version: Older versions of Outlook (2013, 2016) have the same feature but slightly different menu paths. The new Outlook for Windows (the rebuilt version rolling out as of recent updates) aligns more closely with the web experience.
- Sync behavior: Blocked senders lists don't always sync seamlessly across devices, particularly when mixing the desktop app, web app, and mobile.
🔒 When Blocking Isn't Enough
If someone is harassing you or you need to ensure zero contact rather than rerouted-to-junk contact, Outlook's built-in blocking has limits. Messages still arrive on the server — they're just filtered before you see them. For serious situations, contacting your email administrator or the sender's email provider directly may be necessary.
For everyday unwanted mail, knowing whether you're dealing with a specific address, a domain, or general spam patterns will determine which tool in Outlook's junk email system is actually the right fit for your situation.