Hi List,

I have a dumb sendmail question, and I'm wondering if anyone can point me in the right direction (besides "sendmail list is two doors down on the left" ;-).

One of our clients has a bunch of servers -- CentOS 5 -- that are on only a private network that's NATted to the outside world -- that is, those servers can initiate outbound connections fine, but don't have valid IPs / hostnames as far as the outside world is concerned.

The problem is the hostnames of these machines don't exist in real DNS anywhere, so when they try to send mail to the outside world, other mail servers are seeing an invalid domain in the from address and summarily rejecting the messages (which makes sense).

I need to figure out how to tell sendmail, when sending outbound messages, to use the domain name "example.com", instead of "subdomain.example.com". It would seem simple in /etc/mail/sendmail.mc:

MASQUERADE_AS(`example.com')dnl LOCAL_DOMAIN(`example.com')dnl FEATURE(`masquerade_envelope')dnl FEATURE(masquerade_entire_domain)dnl MASQUERADE_DOMAIN(betsy.example.com)dnl

(Followed by a make -C /etc/mail; service sendmail restart)

This doesn't seem to work. The odd thing is that, when I send a message out to an external address of mine, the bounce back to root *does* get through successfully -- the from address at that point is "MAILER-DAEMON@example.com" so it allows it.

Thoughts? I'm thinking I'm missing something realllllllly basic.

best, Jeff