This thread might help you: Re: Global SMTP settings
The SMTP settings are defined in each Alert Actions. A way to change at once the Alerts SMTP settings would be to run a SQL Script to update the Target field of the Emails Action in the ActionDefinitions table for the Advanced Alerts.
The Advanced Alert FrontEnd does not allow you to edit the SMTP settings for multiple alerts at once.
I am not sure about the Basic Alerts and the Reports...I need to make further tests.
EDIT: edited table name from AlertActions to ActionDefinitions as per cbomholt post.
1.) For anyone else reading this, it's in the ActionDefinitions table, not the AlertActions table (my AlertActions is empty).
Package Orion NPM v9 SL2000 Version 9.1.0 Release Orion Version 9.1.0 - October 2008
2.) Please submit this as a feature enhancement request. This is a very unnecessary pain to change this setting. It's available as a global SMTP setting in every single other application I manage.
I ran into the same problem when the mail relay assigned to 50+ advanced alerts crapped out. I bit the bullet and created a "OrionMailRelay" entry in the local Hosts file of the Orion server and pointed that to the SMTP Mail Relay server.
Then I sucked it up and edited the all alerts, I was a lot of work, but now that its done changeing the SMTP server is as simple as editing one line in the Hosts file.
It would be a nice feature to have a "Global SMTP server" setting though.