Mark, This turned out to be our external firewall. Since we are using O365. I was able to successfully telnet to port 25, but when sending e-mails, it was going outside and had to come back in. I then had to change some settings on our F5 and now the traffic is finally flowing through to the server.
Now I am getting this error in mail.log. I have changed quite a few settings to try and not bother you anymore, but nothing seems to be working. Hopefully this will be an easy one for you. The unknown IP address is our F5 where the mail is coming through.
2024-11-13T20:31:15.988423-06:00 lstprdls01 postfix/smtpd[2261655]: connect from unknown[10.18.3.105] 2024-11-13T20:31:16.486460-06:00 lstprdls01 postfix/smtpd[2261655]: disconnect from unknown[10.18.3.105] ehlo=1 quit=1 commands=2 2024-11-13T20:31:18.246010-06:00 lstprdls01 postfix/smtpd[2261655]: connect from unknown[10.18.3.105] 2024-11-13T20:31:18.708146-06:00 lstprdls01 postfix/smtpd[2261655]: NOQUEUE: reject: RCPT from unknown[10.18.3.105]: 550 5.1.1 <joetest@listservnew.luc.edu>: Recipient address rejected: User unknown in local recipient table; from=<jkoral@luc.edu> to=<joetest@listservnew.luc.edu> proto=ESMTP helo=<CO1PR03CU002.outbound.protection.outlook.com> 2024-11-13T20:31:18.852290-06:00 lstprdls01 postfix/smtpd[2261655]: disconnect from unknown[10.18.3.105] ehlo=2 mail=1 rcpt=0/1 rset=1 quit=1 commands=5/6