Sendmail configuration for relaying on SMTP gateway

[Marc Riley]

We have 2 hosts running sendmail 8.12 which are used as SMTP gateways, relaying all external email for ourdomain.com to the internal MS Exchange server. Through recent acquisition, we are now also required to relay email for newdomain.com internally to this Exchange server, however the domain itself remains externally owned & managed.

An MX record is to be put in place for external DNS which will route to the SMTP gateways, however I'm getting a little confused reading doco/articles as to what is required on the gateways themselves. From what I can see, I need to recompile the sendmail.cf with the "FEATURE mailertable" enabled, then configure mailertable with

newdomain.com smtp:[xx.xx.xx.xx]

where xx. is the Exchange server.

Is this all that is required? Do I need to create an internal DNS zone for the new domain containing an MX record, or is that redundant?

Hopefully this is all clear. Appreciate any help.

THanks

[Rajeev Shukla]

Yes thats right, as far as sendmail is concerned you need a pointer (MX Record) for the new domain to route all mails for that domain to SMTP gateway and on the sendmail on SMTP Gateway you enable the mailertable feature and have the entries
newdomain.com esmtp:[xx.xx.xx.xx]
and then make the mailertable.db file and restart the sendmail
Now i dont know about exchange..just see that your exchange server receives and proccess the mails for the newdomain.com