Hi ntozier
IMAP is enabled on the account. It looks like the issue is related to MS disabling Basic Auth for Tenancy in favor of OAUTH2. POP+SSL works and I am able to fetch the emails into OST and even delete emails. SMTP Auth also works and OST is able to send emails. We need the IMAP functionality to move the emails to another folder once fetched but that function is a 'nice to have' for now.
I have a few steps in the plan:
Enable IMAP for the Tenancy:
- Use Help and Support at bottom right of O365 Admin Screen and input Diag: Enable Basic Auth in EXO
- Click on Run Tests and enable only IMAP once tests completed
Create a Block Basic Auth Authentication Policy and apply to allow Mailboxes (Check Sign-Ins in Azure AD to ensure it is not used)
Create an Allow Basic Auth Authentication Policy and apply to the Shared Mailbox User
Will update this post once completed.
Cheers