We have a mail server that has multiple real IPs assigned to a single card. For this docuement i will refer to them as IP1 (220.127.116.11) and IP2 (18.104.22.168). All internal users get to the machine on its primary ip (IP1) because accessing it via name resolves to this address. All mail functions are setup to only work on IP2, a netstat does confirm that 25 and 110 are only running on the IP2 interface. Also our external DNS has the correct IP2 number for the MX (the MX points to an alias mail.domain.com which in turn is IP2). The internal machine is called internal.domain.local. When i send a message outbound and rip the header apart i find IP1 in the header information. This is causing serious issues sending mail to places like gmail.com and aol.com since they do a full RDNS trace back to your mail server. They are getting IP1 which has no MX or RDNS and not IP2 as the server is setup to do.
I feel like i am just missing something here, but another set of eyes might help. Any suggestions?
Please send responses directly to me at <email address removed by sembee>