I'm not sure if this is what you are looking for, but you can change the email template for Contract Workspaces via "Manage > Administration > Project Manager > Email administration" if you have authorization to do so.
This will allow you to change the generic email message sent to recipient of Contract Expiration notification. Emails sent on expiration are grouped into one email, so if you have 3 contracts that expired same day for same person to be notified then the person will get one consolidated email with the content listed 3 times within the body of the email. You can use your own text and add tokens (variables) that add Ariba content to the message.
Thanks for prompt response Christian!