SmarterTrack's OAuth integration should not be requiring this of you, and it sounds like you may be encountering an issue with the authentication token that was issued. What is prompting the OAuth re-authentication process; are you seeing SMTP/POP logs that indicate the authorization has expired?
I did a fairly extensive deep dive into O365 setup and configuration to test these integrations but I don't remember seeing a setting or configuration that might limit the length of time on that side either. I am going to do a little poking around though to see if I can find something on Microsoft's side that might govern this and I'll let you know what I find!
Kyle Kerst
IT Coordinator
SmarterTools Inc.
www.smartertools.com