I setup a mail server for our company, i used "Released 5.0.5_GA_2201.RHEL4_2008041732 CentOS4 FOSS edition"
mail server is behind the Nat firewall and i publish my email to internet.
My problem is I can get mail and send mail from LAN network by MS outlook 2003, but when I go to business, I can not send email from MS Outlook.
I checked /var/log/zimbra.log file on my email server, It report that
"Jul 22 08:11:11 hcmcexch2 postfix/smtpd: NOQUEUE: reject: RCPT from unknown[126.96.36.199]: 450 4.7.1 Client host rejected: cannot find your hostname, [188.8.131.52]; from=<email@example.com> to=<firstname.lastname@example.org> proto=ESMTP helo=<mypc>
Jul 22 08:11:16 hcmcexch2 postfix/smtpd: disconnect from unknown[184.108.40.206]"
Please tell me how i can fix this problem