Comcast of course blocks incoming port 25 as well. I pay to have easydns deliver over SMTP to an alternate port. This means I can't really do effective spam f

Comcast of course blocks incoming port 25 as well. I pay to have easydns deliver over SMTP to an alternate port. This means I can't really do effective spam filtering / denying at the connection level as the connecting server is always easydns. (Although denying spam that then bounces often is misidentified as originating spam... so...) What best practices do others do when still hosting SMTP at home?