On 10/18/2012 3:32 PM, Steven Kiehl wrote:
Hi,
I'm using dovecot 1.2.9 in a postfix/dovecot setup and I'm having issues with receiving spam where the "from" header contains an address like accounting@mydomain.com. Is there some way I can filter out these emails coming from outside our network with an account associated with our network which doesn't exist? Do I just need to configure some custom process to evaluate these addresses, or is there some way either in dovecot or spamassassin to do this?
Thanks,
Steve K
This should be dealt with in postfix or SpamAssassin, not dovecot, and there are likely other, better ways to detect this particular spam rather than mucking with the From: header.
Sometimes mail arrives with a header something like From: accounting and postfix appends @$myorigin to the unqualified address while passing the mail through your content_filter.
The fix for that is to set in your postfix main.cf remote_header_rewrite_domain = domain.invalid so that unqualified addresses will be rewritten with a known domain. Don't be tempted to reject such mail outright since you'll reject a significant amount of non-spam mail.
Another thing to consider setting in postfix main.cf is: smtpd_reject_unlisted_sender = yes which will reject invalid envelope senders in your domain. (Note the difference between envelope sender and the From: header.)
-- Noel Jones