a customer of mine is using Nokia with Zimbra; the only issue is that Nokia use an adressess pool to handle imap & smtp.
As you can see here:
xxxxx was authenticated with ip 220.127.116.11 then 18.104.22.168;
2010-03-11 08:24:43,455 INFO [ImapServer-5746] [email@example.com;ip=22.214.171.124;] imap - user firstname.lastname@example.org authenticated, mechanism=PLAIN
2010-03-11 08:31:34,921 INFO [ImapServer-5749] [email@example.com;ip=126.96.36.199;] imap - user firstname.lastname@example.org authenticated, mechanism=PLAIN
at 2010-03-11 08:31:34 he sent out an email:
with ip 188.8.131.52, and get back in his face 554, Relay access denied
Mar 11 08:31:34 webmail postfix/smtpd: NOQUEUE: reject: RCPT from unknown[184.108.40.206]: 554 5.7.1 <email@example.com>: Relay access denied; from=<firstname.lastname@example.org> to=<email@example.com> proto=ESMTP helo=<vienec6mg02>
what can be done to get rid of this issue?