[Mimedefang] DNS and MX records
Kris Deugau
kdeugau at vianet.ca
Tue May 9 10:51:38 EDT 2006
netguy wrote:
> Receintly I updated DNS for a few domains. My registrar gives the
> option of assigning an IP addy for domain.tld without having an alias:
> mail.domain.tld Ok, says I, lets give it a go. Bam! Slam, Spam
> started invading my privacy. This leads me to believe either:
> 1. Mail ( spam ) in this case is being sent to domain names without
> doing MX lookups.
Yep. Spamware will certainly blindly open a connection to port 25 on
<domain.tld>, rather than sorting through MX records. Personally, I
think it's "better" to have that A record in place, spam notwithstanding.
Garbage is spewed out to <dictionary words>@<domain.tld> - for a time,
it looked to me as if some ratware was actually literally iterating
through ALL possible usernames composed of a-z and 0-9. If you've got a
catch-all address, you may want to rethink that. If you're running
MIMEDefang, you may want to look into fleshing out filter_recipient().
-kgd
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