Hello Ram,
If you already loaded the users without modifying the preferences before the load you will be stuck with the OOTB defaults. Unfortunately, users will need to manually modify their notification preferences by clicking the Preferences link and selecting Notification Preferences. This is not something that can be done acting as other users. I would recommend creating a Quick Reference Guide to send to the business that provides your recommendations if you're in a production environment. The emails being sent in summary is a preference that can be changed in the same area (e.g. notification preferences). In Addition, if you're in a test environment Ariba recommends placing the following email address to prevent messages from going out to users: no-reply@ansmtp.ariba.com.
Contract Notifications can be customized by an Administrator by accessing Manage > Administrator > Project Manager > Project Email Templates. From this screen you can modify the content of the message so that it makes more sense for your end users. You can also grab fields from the Workspace and populate the emails with the information contained in that specific workspace (e.g. Contract Id, Effective & Expiration Date ect).
Let me know if you have additional questions. Thanks,
Robert Myroniuk
Ariba Consultant - Source to Pay (S2P)
Ariba, an SAP Company