This morning, exclamation marks appeared next to all of my Exchange accounts in Apple Mail on my Mac. The accounts still work normally in Mail on iOS, Outlook, and webmail, but macOS Mail is no longer syncing properly. I've tried deleting and re-adding the accounts, rebuilding the mail database by removing the envelope index files, and checking Connection Doctor. Connection Doctor reports that everything is fine, but messages still aren't downloading. Is anyone else seeing this today, or has found a reliable fix?
4 Answers
The issue may be related to Microsoft 365’s Exchange connectivity changes, including the retirement of older Exchange Web Services access. Re-enabling EWS through the tenant didn’t fix it for at least one person, though, so that may not be the whole explanation.
Deleting and rebuilding the Outlook or Exchange account didn’t help several people, and the same behavior was reported across multiple Macs. That points to a service-side compatibility or authentication problem rather than a damaged local mailbox database.
This appears to be a wider issue affecting Exchange accounts in macOS Mail rather than an isolated account problem. Several people reported it starting around the same morning, while iOS Mail, Outlook, and webmail continued working. Rebuilding the mailbox or removing and re-adding the account didn’t resolve it for everyone.
For some users, Mac Mail could still send messages but wouldn’t receive new mail. Connection Doctor continued to show successful connections, making it unreliable as an indicator in this case. Outlook on Mac or Windows, webmail, and iOS Mail remained usable workarounds while waiting for the Mac Mail issue to be resolved.
That matches what I’m seeing too. The problem started suddenly, and it affects multiple accounts and Macs in the same office.