Sunday, October 18, 2015

Fighting spam with SpamAssassin, procmail and greylisting

On my private server we use a number of measures to stop and prevent spam from arriving in the users inboxes:
  • postgrey (greylisting) to delay arrival (hopefully block lists will be up to date in time to stop unwanted mail, also some senders do not retry)
  • SpamAssasin to block mails by scoring different aspects of the emails. Newer versions of it has URIBL (domain based, for links in the emails) in addtition to the tradional RBL (IP based) block lists. Which works better. I also created my own URIBL block list which you can use,
  • Procmail. For users on my server, I recommend this procmail rule:
    * ^X-Spam-Status: Yes
    It will sort emails that has a score indicating it is spam into mailbox "crapbox".
  • blocking unwanted and dangerous attachments, particularly for Windows users.