Windows
Outlook on the PC would not accept the work account
The user could sign into the account on a phone but not in Outlook on the PC. Reauthenticated the Microsoft 365 work account on the machine, corrected the default email address in Outlook, and confirmed send/receive worked.
Killed once by someone from XL.net, on 2026-03-08.
Affects
Versions
- Windows
Apps
- Outlook
- Microsoft 365
What you see
- Outlook sign-in fails on the PC for the work account
- The same account still signs in on a phone
- Mail does not send or receive normally in Outlook until the account is reauthenticated
Why it happens
Likely Stale or incorrect Outlook/Microsoft 365 authentication on the PC, with Outlook using the wrong default email address until it was corrected
When it shows up
A Windows PC cannot sign into Outlook for a work Microsoft 365 mailbox, but the account still works on mobile
You are in this case if:
- Outlook shows a sign-in failure or keeps asking for credentials on the PC
- The same mailbox can still be opened on a phone or mobile app
- Outlook is set to the wrong default email address
1 fix below
The steps that killed it
The steps are behind a quick check
There are two ways in and both take a few seconds. Signing in opens the steps on every bug page; so does reading the picture.
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Someone from XL.net killed this on a Windows computer on 2026-03-08. It is written up from that one repair, so it cites no outside page.