On Thu, Dec 01, 2022 at 03:23:52PM +0000, David Dolan wrote:
> We have two customers who we're unable to receive email from. It's
> failing the helo lookup as it can't resolve the hostname in the helo
> message. Helo command rejected: Host not found;
Not surprising, too many systems have fictional HELO names.
> The postfix configuration for helo checks is as follows. It's failing on
> reject_unknown_helo_hostname
>
> smtpd_helo_required = yes
> smtpd_helo_restrictions =
> reject_non_fqdn_helo_hostname
> reject_invalid_helo_hostname
> reject_unknown_helo_hostname
This is a not a recommended blanket setting. You could *selectively*
apply reject_unknown_helo_hostname to some client IPs or some sender
addresses, but as a global restriction this is far too prone to
false positives.
> The hostnames in the helo messages are resolvable with the PTR and A record.
PTR has nothing to do with this, that's: IP -> name -> IP.
Does the HELO name resolve to at least one address?
In any case, drop the "reject_unknown_helo_hostname" restriction it is
not a good idea.
--
Viktor.
