Exchange is supposed to support UIDPLUS, but information on the Internet is all over the place about this. I'll turn on IMAP logging against our M365 account to see if it's being reported as supported.
Bug 2009013 Comment 26 Edit History
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Exchange's IMAP implementation is supposed to support UIDPLUS, but information on the Internet is all over the place about this. I'll turn on IMAP logging against our M365 account to see if it's being reported as supported.