Quoting netbsd@ns.purk.ee (netbsd@ns.purk.ee):
> Postfix is really greate!
> Welcome to the world of misconfigured dns ;-)There is a
> good reason to REJECT fake HELO/EHLO dns names.
> 
> Aug 24 22:32:58 ns postfix/smtpd[17544]: 6CF4BAEC4: reject: RCPT from
> 80-235-40-213-dsl.mus.estpak.ee[80.235.40.213]: 450 <KOHV>: Helo command
> rejected: Host not found; from=<JURI123456@HOT.EE> to=<purk@purk.e$Aug 24
> 22:32:59 ns postfix/smtpd[17544]: disconnect from
> 80-235-40-213-dsl.mus.estpak.ee[80.235.40.213]

Yeah!  Screw the RFCs!  Customize SMTP to your own wants and
needs.  Blocking legit mail?  who cares!  I stopped lots of
spam.


Welcome to the world of the consumer Internet where reverse
DNS is, er, optional (and per the SMTP & DNS RFCs, it *is*)
and where real players in WRITING the RFCs and advancing the
internet are on machines with providers who don't have rev DNS
or any inclination to fix it.

I tag said mail (odd HELO name, no reverse DNS) and it adds a point
to the mail (spamassassin rules).  the content of legit mail usually
keeps it from going over the edge.