TL;DR

Spam filters use AI to detect patterns in junk email—suspicious links, sender reputation, content keywords, and user behavior. They block 99%+ of spam but occasionally catch legitimate emails too.

How AI spam filters work

Analyze sender:

  • Is the sender known?
  • Does the domain have a bad reputation?
  • Is it a mass sender?

Scan content:

  • Suspicious keywords ("free money," "click here")
  • Links to known phishing sites
  • Attachments with malware signatures

Check user behavior:

  • Do other users mark this sender as spam?
  • Do you usually read emails from this sender?
  • Is this sender in your contacts?

Machine learning:

  • AI learns from billions of emails
  • Patterns that predict spam vs. legitimate
  • Improves over time

Why it works so well

  • Trained on millions of spam examples
  • Updates constantly as spammers evolve
  • Learns from your actions (marking spam/not spam)

Why it sometimes fails

False positives (good emails marked spam):

  • Overly promotional language
  • New sender with no reputation
  • Unusual formatting or links

False negatives (spam gets through):

  • Clever spammers mimic legitimate emails
  • New spam tactics AI hasn't seen yet
  • Personal attacks (targeted phishing)

How to help your spam filter

  • Mark spam when it gets through
  • Mark "not spam" when legitimate emails are caught
  • Add trusted senders to contacts
  • Check spam folder occasionally

What's next

  • AI in Everyday Life
  • Phishing and Scam Detection
  • Email Security Best Practices