Hi,
I have a question regarding restrictions I can place on EHLO in the
smtpd_helo_restrictions parameter.
I have a Postfix server that is Internet facing. I periodically receive e-mail
where the other MTA sends a EHLO of an address literal. I checked RFC 5321
(SMTP), and confirmed that this is valid (because I imagine someone might have
a MTA internal to their network and they might not have DNS names for
everything), however in nearly almost every case that an address literal is
presented, it’s from someone attempting to deliver spam.
My initial thought was I could stop this with:
main.cf
. . .
smtpd_helo_restrictions =
. . .
reject_non_fqdn_helo_hostname,
. . .
…however when I checked the Postfix documentaion[1] for this parameter I read:
Reject the request when the HELO or EHLO hostname is not in
fully-qualified domain *or address literal form* . . .
I glanced briefly to see if there were any other ways to restrict this but none
seemed evident to me.
Is there a way to achieve this ? Alternatively, should I not be attempting to
do this because legitimate server’s sometimes EHLO address literals ?
Thanks,
- J
[1] http://www.postfix.org/postconf.5.html#smtpd_helo_restrictions
