Your mailbox will automatically move 99% of incoming junk mail to your spam folder to keep your inbox clean*. But if you’re receiving a lot of the same spam over and over, finding legitimate emails that were flagged as junk can feel like an impossible task. Whether your email address was part of a data breach or you ended up on a spammer’s list some other way, keeping your spam folder in check shouldn’t turn into a second job.
Setting up custom message rules in your mail app can help you find and delete spam messages based on details like the sender’s name or the subject line and automatically remove them, leaving only a handful of messages for you to review for false positives.
Before You Start
- Custom filters will automatically check your inbox for any messages that match your rules. But messages in your spam folder were moved out of the inbox before they were delivered to your mailbox, so custom filters will not automatically check the spam folder. You will need to run the rules manually on your spam folder to allow your mail app to check for messages that match your rules.
- Instead of trying to block specific email addresses, we recommend creating rules based on the from name or subject line since spam is rarely sent from the same address more than a few times.
- Before creating filters, sort your spam folder by from name or subject to quickly find the junk mail that you receive the most.
- If you connect to mail using the older POP3 protocol, these rules will not work. Switch your account to IMAP in order to access the Spam folder in Outlook.
Windows
Outlook Classic Thunderbird
MacOS
Mail for MacOS Thunderbird
*If your inbox still receives a lot of junk mail, consider increasing your overall spam filter level.
Posted April 16, 2026
