[CentOS] dumb sendmail question -- how to get outbound messages to
use "example.com" instead of hostname?
jpotter-centos at codepuppy.com
Mon Jul 2 17:43:27 UTC 2007
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:
(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 at example.com" so it allows it.
Thoughts? I'm thinking I'm missing something realllllllly basic.
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