From a local ISP; I’m sure this seemed like a great idea at the time.
220 mx2.avalonworks.net ESMTP Postfix helo hostname-of-internal-mailserver.mati.ca 250 mx2.avalonworks.net mail from:<rich@mati.ca> 250 Ok rcpt to:<test@igs.net> 554 <hostname-of-internal-mailserver.mati.ca>: Helo command rejected: Host not found
Er, sorry, what failed? I guess it forgot to tell me way back
then. I thought for a minute that it waited until RCPT to be able to
accept mail to postmaster in any case, but no, that fails there too.
I particularly like how an unsuccessful DNS lookup causes a permanent mail
failure, because DNS is always reliable.
Besides, no-one ever sends mail from a host that can’t receive mail
(say, behind NAT, maybe), and spammers would never put a resolvable
address in HELO.
On a hunch:
220 mx2.avalonworks.net ESMTP Postfix helo mail2.igs.net 250 mx2.avalonworks.net mail from:<rich@mati.ca> 250 Ok rcpt to:<test@igs.net> 250 Ok
Yes, spammers would never ever just put the destination address
in the HELO. Sometimes I think antispam efforts exist to provoke
a cold war. (See also “challenge-response”).
2 responses to “I guess you didn’t want my mail, then.”
Those guys are such clowns… I deal with them in the role of implementation support for one of their suppliers and I’ve got to say I’ve been less than impressed with the tech team.
Ugh, I had to use IGS for dial-up in Waterloo before DSL was readily available (like…5 years ago) and it was awful.