Steps to improve your spam filtering

This post is a summary explaining the common measures people can take to improve the spam filtering in their account.

1. Turn on advanced spam filtering

   • Go to the Options -> Spam / Virus protection screen and
     switch from “Basic” to “Normal”, “Aggressive” or “Custom” level
     filtering (subscription accounts only)

2. Avoid using forwarding services

   • If you forward email from an old email address, tell people to
     use your @fastmail.fm/@sent.com/etc address instead and close
     down forwarding from the old system.
   • If you use your own domain, point the MX records for your
     domain
     directly at our servers (Enhanced or family/business accounts
     only)

3. Report spam and non-spam emails

   • If you report more than 200 spam and 200 non-spam emails, it
     will activate your personal bayes
     database.
     This will significantly increase the scoring accuracy of the
     spam filter on your email
   • See the bottom of the Options -> Spam / Virus
     protection screen to see how many spam and non-spam emails
     you’ve reported
   • If you use IMAP mostly, setup auto-reporting on folders. Login
     and go to Options -> Folders. Set the “Learn as
     non-spam” property on folders that you store known non-spam
     emails in (eg folders you archive emails into). Create a folder
     called “Learn spam”, and set the as “Learn as spam” and
     “Purge > 7 days old” properties on it. Then from your IMAP
     client, drag any spam emails you receive into that folder to
     learn them + delete them

4. Add known senders to your address book

   • Email from senders in your address book get special
     treatment.
     They avoid
     greylisting
     and get a reduced spam score
   • The checking will occur on the SMTP MAIL FROM envelope, the
     “From” header, and the “Sender” header

A more detailed post will follow explaining the technical underpinning of these shortly.