Receive Email problem after IP change

Hi, recently I moved the server to a new IP.
Everything is working OK except receiving emails.
I searched in forum and I didn’t find a solution.

Operating system Ubuntu Linux 10.04.1
Webmin version 1.540 Virtualmin version 3.84.gpl GPL

The emails remain in queue.
MAILER-DAEMON “” […] said: 450 4.7.1 Client host rejected: cannot find your hostname, [“INTERFACE EXTERNAL IP”] (in reply to RCPT TO command)

/etc/postfix/ - seams to be OK ( mydestination & myhostname with FQDN
/etc/postfix/virtual - contain all addresses
/etc/hosts - contain the IP and FQDN

There is something I don’t figure out, please can you help me?

seams that was an error in postfix config, the stand alone hostname was missing:
mydestination =,, localhost

working config:
mydestination =,, localhost, primus

I just had a similar problem (server not sending email after IP address change)…

Turns out, after I contacted my ISP to have reverse-DNS enabled/corrected for my new IP address, I suddenly got 100’s of emails in the few minutes…

I had “reject_unknown_client_hostname reject_unknown_reverse_client_hostname” in the file.

Live and learn.