Carles Pina i Estany:
> root@mail:~# nslookup 188.39.73.166
> 166.73.39.XXX.in-addr.arpa name = mailcluster.zen.co.uk.
That is sufficient to satisfy reject_unknown_reverse_client_hostname.
But you have also configured reject_unknown_client_hostname. That
requires that mailcluster.zen.co.uk resolves to the client IP
address 188.39.73.166:
$ host mailcluster.zen.co.uk.
mailcluster.zen.co.uk has address 212.23.6.67
mailcluster.zen.co.uk has address 212.23.3.121
And that clearly does not satisfy reject_unknown_client_hostname.
You can't use reject_unknown_client_hostname for that
site, if you want to receive their email.
Wietse
