Steps to improve your spam filtering

Product

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.