Hello,

I have mail services: main and a sub-domain running on two separate servers, with one on sendmail and the other on postfix+cyrus. I wish to run both the domains under one host, and since they are in production, wish to retain separate MTAs, one for each domain. I have a single NIC on this host and wish to share port 25 between the two. Kindly let me know how this can be achieved.

Thanks in advance

Howdy Gowranga,

Two services can't share the same IP:port combination.

Your only option, if you must keep two MTAs would be to use one running on port 25 to forward to the other running on a different port for certain domains. Both Sendmail and Postfix can do this, though I think it's easier in Postfix (almost everything is easier in Postfix, unless you speak the super-secret-encrypted Sendmail configuration lanuage--even the m4 file is a bit baffling to me).