Hi Chris,
Thanks for the test and information.
Regarding the current situation, I’d like to collect the following information:
1. Which type of migration did you use, Cutover, Staged or Hybrid migration?
2. Is Single Sign-On (SSO) deployed in the organization?
2. What is the status of the current users in local AD, regular user, mailbox or mail-enabled user?
3. Could you run a test to start Outlook when the firewall is disabled temporarily?
4. I understand it takes a long time to start Outlook. Could you tell me whether it takes a long time to run the E-mail AutoConfiguration test in Outlook?
Best Regards,
Bruce Zhou