These messages can be found in the log or are shown when selecting folders since April 10/11. (Not for everyone, I don't have this problem myself).
You have exceeded the available concurrent connections for your account. Try again once your other requests have completed.
The problem is described here:
https://learn.microsoft.com/en-us/answe ... oduces-a-5
https://github.com/OfficeDev/ews-managed-api/issues/294
https://github.com/OfficeDev/ews-managed-api/issues/293
... a solution is not yet known.
Microsoft 365 Throttling problems since April 10, 2023 with Public Folders
Re: Microsoft 365 Throttling problems since April 10, 2023 with Public Folders
Das Problem wurde durch Microsoft behoben.