How to change url in body email service desk
You'll need to do this through the Alert Manager.
1) Settings
2) Manage Alerts
3) Select Alert you'd like to edit - Note: If it's an "Out-of-Box" alert, you'll need to Duplicate and Edit.
4) Once you finish setting up/editing the Properties, Trigger Condition, Reset Condition, and Time of Day you'll need to edit the "Trigger Actions"
5) Click the "Add Action" button
6) Choose the option for "E-mail a Web Page"
7) Fill out all necessary options and information
8) Save the alert
9) Do the "I just won at alerting" dance, because you did just win at alerting. You won big time!
Hope that helps!
-Brandon