[Dovecot] Emails from invalid local accounts

[Ben Morrow]

At  4PM -0400 on 18/10/12 you (Steven Kiehl) wrote:
> 
> 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 at 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?

You want to do this in Postfix, with either the
smtpd_reject_unlisted_sender parameter or the reject_unlisted_sender
policy in smtpd_sender_restrictions. You will need to make sure Postfix
has access to the list of valid mailboxes at your domain, which it
should have already for recipient checking.

Ben