helo command rejected

[David Dolan]

Hi,

We have one customer who we're unable to receive email from.
It's failing the helo lookup as it can't resolve the hostname
Helo command rejected: Host not found;

The postfix configuration is as follows
smtpd_helo_required = yes
smtpd_helo_restrictions =
reject_non_fqdn_helo_hostname
reject_invalid_helo_hostname
reject_unknown_helo_hostname

The hostname in the smtp message is resolvable for the PTR and A record.
However the A record does have 32 IP addresses in it's DNS record. I don't know if that's an issue which causes a problem with the verification. It's the only thing I find unusual.

Has anybody come across this before and any idea how to resolve it?

Thanks
David

[David Dolan]

Hi,

Just wondering if anybody has ideas here?
Is it allowed that the A record of the hostname in the helo message resolve to 32 IP addresses.
Could that be the reason why the Postfix sees it as unknown and rejects it?

Thanks
David