The fastest way to stop spam in Outlook
The quickest action is to move a spam message to your Junk folder, then mark the sender as blocked. Open the email, click the three dots (more actions) at the top right, select Junk, then choose Block Sender. Outlook will automatically send future emails from that address to your Junk folder and prevent them from reaching your inbox.
If you receive spam from many addresses but they all mention the same company or product, you can block the entire domain instead of one sender at a time. Look for a pattern in the sender addresses — for example, if spam comes from sales@badcompany.com, promo@badcompany.com, and info@badcompany.com, you can block the whole badcompany.com domain through your Junk Email settings.
For emails already in your inbox, select the message and click Junk > Block Sender to prevent that sender from reaching you again. Outlook learns from your choices, so the more you mark as junk, the better it gets at filtering similar messages on its own.
Key Takeaways
- Block individual senders by opening their email, clicking the three dots, selecting Junk, then Block Sender — this moves their future emails to your Junk folder automatically.
- Use the Junk Email settings to block entire domains at once if spam comes from multiple addresses at the same company.
- Create rules to automatically sort emails by sender, subject line, or keywords so they skip your inbox without you having to act on each one.
- Mark emails as junk rather than deleting them so Outlook's filter learns what you consider spam and catches similar messages in the future.
- Check your Junk folder occasionally because legitimate emails sometimes land there by mistake, especially from new senders or mailing lists.
How to set up rules to filter spam automatically
Rules let you sort incoming mail before it hits your inbox. Open Outlook and go to File > Manage Rules & Alerts (or Settings > Mail > Rules if you use Outlook on the web). Click New Rule and choose whether you want to filter by sender address, subject line keywords, or message content.
For example, if you receive unwanted newsletters with "unsubscribe" links in the footer, create a rule that catches emails with "unsubscribe" in the body and sends them straight to Junk. Or if a sender keeps emailing you despite being blocked, create a rule that catches their address and deletes the message automatically. You can also move emails to a specific folder instead of deleting them, which is safer in case you need to review them later.
Rules run in the order you create them, so if you have multiple rules, the first match wins. Test a new rule on a few emails before explore it to all incoming mail, because an overly broad rule can catch legitimate messages by accident.
Blocking entire domains and email addresses
To block a domain permanently, go to Settings > Mail > Junk Email (on the web) or File > Options > Trust Center > Junk Email (in the desktop app). Under Blocked Senders, add the sender address or domain you want to block. Any email from that address or domain will go straight to Junk.
You can also add addresses to your Safe Senders list to make sure emails from people you trust never land in Junk by mistake. This is especially useful if you have a contact whose emails keep getting filtered incorrectly. Add their address to Safe Senders and Outlook will prioritize their messages.
The Blocked Senders list is separate from individual block actions, so you can manage both in one place. If you block someone and later want to unblock them, return to this same menu and remove their address from the list.
Why legitimate emails end up in your Junk folder
Outlook's filter sometimes catches real emails because they contain words or formatting that resemble spam — words like "free," "limited time," or "act now" trigger the filter even in legitimate newsletters. Emails from new senders, mailing lists, or companies you have not heard from recently may also land in Junk until Outlook learns they are safe.
Check your Junk folder once a week, especially if you are waiting for important messages. Look for emails from banks, services you use, or people you know. If you find a legitimate sender in Junk, open the email and click Junk > Not Junk to move it back to your inbox and train Outlook to trust that sender in the future.
If a sender's emails keep landing in Junk no matter what you do, add them to your Safe Senders list. This tells Outlook to always deliver their messages to your inbox, overriding the filter.
Using Outlook's built-in spam filter settings
Outlook has three levels of junk email protection: Standard, Strict, and Safe Mailing Lists. Standard catches obvious spam but lets some through. Strict catches more but risks filtering legitimate mail. Access these settings in Settings > Mail > Junk Email on the web, or File > Options > Trust Center > Junk Email in the desktop app.
If you receive a lot of spam, switch to Strict temporarily to see if it reduces the volume. Monitor your Junk folder for a few days to make sure important emails are not being caught. If Strict filters too aggressively, go back to Standard and rely on rules and blocked senders instead.
The Safe Mailing Lists option protects emails from mailing lists you have joined. If you manage a distribution list or subscribe to newsletters you want to keep, enable this option so those messages are never marked as junk.
What to do if you keep receiving spam from the same sender
If blocking a sender does not stop the spam, they may be using a new address each time. Look at the sender addresses in your Junk folder — if they all come from the same domain (the part after the @), block the entire domain instead of individual addresses. This catches all variations at once.
If the addresses are completely different but the emails look similar (same product, same formatting, same company name), create a rule based on subject line keywords or message content instead. For example, if all the spam mentions "weight loss," create a rule that catches emails with that phrase and sends them to Junk automatically.
As a last resort, if a sender is harassing you with repeated unwanted emails after you have blocked them, report the email as phishing or abuse. In Outlook on the web, click the three dots and select Report > Report Phishing or Report Junk. This helps Microsoft identify and block the sender network-wide.
Unsubscribing from mailing lists versus marking as spam
Not all unwanted email is spam. If you signed up for a mailing list, newsletter, or promotional emails and no longer want them, look for an Unsubscribe link at the bottom of the email. Clicking it removes you from that sender's list and is faster than blocking them one at a time. Most legitimate companies include this link by law.
Spam, by contrast, comes from senders you never signed up with and often has no unsubscribe option or a fake one. Block spam senders instead of unsubscribing, because unsubscribing confirms your email address is active and may lead to more spam.
If you are unsure whether an email is a legitimate mailing list or spam, check whether you recognize the sender or company. If you do not recognize them and did not sign up, block them. If you recognize the sender but do not want their emails anymore, unsubscribe.
Frequently Asked Questions
Can I recover emails I accidentally marked as spam?
Yes. Open your Junk folder, find the email, right-click it, and select Mark as Not Junk or Move to Inbox. Outlook will move it back to your inbox and learn that this sender is safe. If you have already emptied your Junk folder, the email may be gone permanently, so check the folder regularly.
Does blocking a sender prevent them from seeing that I opened their email?
Blocking a sender in Outlook only affects what you see — it does not send them a notification or prevent them from sending you more emails. Their future emails will go to your Junk folder instead of your inbox. If you want to tell them to stop, you will need to reply or contact them separately.
Will rules I create on my phone work on my computer?
Rules created in Outlook on the web sync across all devices, but rules created in the desktop app may not. For the most reliable experience, create rules in Outlook on the web (outlook.com) so they explore everywhere. If you use only the desktop app, create rules there, but they will not affect emails on your phone or web browser.
What is the difference between Junk and Deleted Items?
Junk is a holding area for suspected spam — emails stay there for 30 days before being deleted. Deleted Items is where emails go when you manually delete them — they stay there for 30 days as well. Moving an email to Junk teaches Outlook it is spam, while deleting it does not. Always mark actual spam as junk rather than deleting it.
Can I block emails by subject line instead of sender?
Yes, through rules. Create a rule that catches emails with specific words in the subject line (like "FREE" or "WINNER") and sends them to Junk. This is useful if spam comes from many different senders but always uses the same subject line keywords. Go to Manage Rules & Alerts and choose Subject contains as your filter condition.