We are on Dynamics 2013, on-premises for two years. Suddenly a user has issues tracking emails. She can track an email before it is sent but from her sent items: "An error occurred promoting this item to Microsoft Dynamics CRM. ... server could
not be contacted or the user has insufficient permissions to perform this action." This started five days ago and she has been doing this for years. No one else is having the problem. Thanks for your help.
I resolved this myself. We are changing domains for email and, even though old and new addresses work, apparently sent items have the new domain. I changed her email address in CRM and it worked.