I have a SUSE 11SP3 in which my apps team is trying to send emails but the SMTP server rejects the traffic from this server. A detailed trace shows that the traffic is going to SMTP server through the virtual IP configured on the physical interface. Actually it has to go through the physical interface. SMTP server was configured to accept the connections from IP/hostname configured on the physical interface.
We tried telnet to the SMTP server with port no 25,
szcld01:/etc # telnet LTC-SMTP-RELAY-PRI.ABCD.NET 25
Connected to LTC-SMTP-RELAY-PRI.TWUTIL.NET.
Escape character is '^]'.
220 EXHWP02.TWUTIL.NET Microsoft ESMTP MAIL Service ready at Wed, 11 Nov 2015 06 :46:46 +0000
250-EXHWP02.TWUTIL.NET Hello [10.179.56.242] ===========>>>>>>> this is the virtual IP
So the apps team suspects this could be the issue behind the problem. My physical IP is 10.179.56.221