[clug] [PMX:#] Sendmail forwarding

[Andrew Pollock]

On Tue, Aug 24, 2004 at 04:59:22PM +1000, Collins, Steve wrote:
> All
> 
> I have a RH9 box running Nagios which is merrily sending internal mail around our network.  However, now I want to get some after-hours mail going.  I have information about an approved SMTP gateway for my use, but not being across sendmail in any real way, have no idea how to relay via the gateway.
> 
> Any and all advice appreciated.

If you want all external mail to go via the gateway, define a smarthost in
your /etc/mail/sendmail.mc thusly:

define(`SMART_HOST', `smtp:[w.x.y.z]')

where w.x.y.z is the IP address of the SMTP gateway.

You then need to rebuild your sendmail.cf, which on Red Hat used to be a
real pain, but may be as simple as running "make -C /etc/mail" these days,
and restart Sendmail.

If you want selective domains to be sent via the gateway, you need to ensure
that you have 

FEATURE(`mailertable')dnl

in your sendmail.mc, and then add rules to your /etc/mail/mailertable file
in the format

example.com	smtp:[w.x.y.z]

You then need to rehash your mailertable file, which may also be as simple
as rebuilding your sendmail.cf, i.e. run "make -C /etc/mail"

Hope this helps. 

http://www.sendmail.org/m4/readme.html is a good source of information.

regards

Andrew