On a local server I have for testing I need to use my isp’s mail server for sending emails. They block port 25 so all mail has to be routed through their server. Luckily they do not require authentication, they use ip based ACL’s so setting up sendmail was a breeze!
All it tooke was opening
/etc/mail/sendmail.mc
adding/changing:
define(`SMART_HOST',`[mail.bellsouth.net]')
and then reseeting the sendmail config via:
m4 sendmail.mc > sendmail.cf
service sendmail restart
Now any mail sent from my machine (system status, php’s mail function, etc) will be routed through my isp’s mail server.