[German]There have been massive problems with Microsoft 365/Exchange Online since March 2025. And some readers and users are complaining that access to mailboxes via the Samsung Mail app is not working. A blog reader sent me a "spooky" solution to this problem (install the Microsoft Authenticator app and disable battery optimization helps).
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Reader reports about the issue
I have been reporting numerous problems with Exchange Online mailboxes within my German and English blogs since February 2025. Microsoft confirmed in incident reports that users of the iOS Mail app were unable to access Exchange Online mailboxes, among other things.
However, I repeatedly received blog readers who complained that they could not access their mailboxes with the Samsung Mail app. In the article Exchange Online- und MS365-Probleme durch Schwachstelle? (März 2025) , I quoted a reader who wishes to remain anonymous with his observations. The reader, himself a tenant administrator for a double-digit number of customers, wrote to me that he had already commented on the problem with the Samsung Mail app in the blog.
However, he can not only observe the problems with one of his customers' European Exchange Online tenants. His wife is also hosted on a US Exchange Online tenant with her mailboxes via her employer (US company) and has the same problems.
The problem: It can hit one mailbox while there are no problems with other Exchange Online mailboxes with the Samsung Mail app. Reader's statement: His wife has both a US and a European M365 account in the Samsung Mail app (same smartphone). There are only problems with the US account. The European account is in the reader's tenant. There are problems with two mailboxes in this European tenant, but not with the woman's mailbox.
The reader said that overall it looks like a global problem, but it does not affect all accounts in a tenant. It is also noticeable that the problem does not occur all the time, but sometimes more and sometimes less frequently.
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Another reader's solution approach
Another blog reader, let's call him Stefan, then contacted me on March 24, 2025 and wrote that he had looked into the problems with the Samsung email app and Microsoft 365 in more detail and wanted to give some feedback (thanks for that).
Problem known at Microsoft/Samsung – no solution
The reader has read countless discussions about the problem on Reddit and came to the conclusion that Microsoft and Samsung are aware of the problem but are blaming each other. The problem only occurs with app version 6.2.01.1 from February 12, 2025, writes the reader. It should work with the previous app version. The reader concluded that there must be a connection with the problems at Microsoft at the beginning of March 2025, as the problem did not occur before then.
Spooky finding: Microsoft Authenticator app battery optimization
The reader wrote that he had come across a very "spooky" cause. An affected person had written on Reddit that there should be a connection with the battery optimization of the Microsoft Authenticator app. This makes sense in a way, because "the text about this function in the app also gives a hint".
The reader had installed the app, but no longer used it as he had switched to 2FA via hardware (YubiKey). As a test, he deactivated battery optimization in the Microsoft Authenticator app under Settings. Even after more than 24 hours, everything works perfectly again.
He then checked another phone with the same problem in a different tenant. Here, the Microsoft Authenticator app was not installed because another app was used for 2FA. In a mad dash, he installed the Microsoft Authenticator app, canceled the setup of the app without accounts and deactivated battery optimization in the app settings. There were no more problems for several hours, so I uninstalled the Microsoft Authenticator app again. After 20 minutes, the problem returned. So I installed the Microsoft Authenticator app and the problem was solved again.
"That doesn't sound very logical, but it works for me now with 2 phones without any problems. Maybe it will help other users too," wrote the reader.
On March 26, 2025, the reader contacted me again by email and wrote: "It's no coincidence, because the synchronization of the Samsung Mail app is now running completely smoothly again on both Samsung devices." The reader then provided me with a link to this discussion on reddit.com with identical results (thanks for that). As the reader notes: "But the fact that simply installing the Microsoft Authenticator app solves the problem is still spooky." I can only agree with that.
A German reader wrote, that probably changing the permissions in the Samsung Mail app in Android, to prevent energy optimizing during battery usage, could also solve the issue.
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