We have a few email notification rules set up to autolog calls with our service desk, the return address for these is server_name@domain_name if the mail bounces for what ever reason the response is undeliverable. Is it possible to change the address that the emails are sent from to our sysadmin group address instead.
Is the server running on Windows?
If so, there's a canned remote action that will allow you to set this up. This is the easiest way.
Look for the "Setup Sending SMTP E-mails - Windows Only" Remote action. You'll be able to specify the "From" account there.