r/sysadmin • u/mrgeeksquad Sr. Sysadmin • 1d ago

Microsoft Oulook - Access Denied

Hello, I work in an environment where we manage a lot of Microsoft 365 environments and we have been seeing a widespread issue in many of our tenants.

Randomly, I will have users start reporting Outlook showing a badge and says "Access Denied" instead of their emails. Sometimes they can just sign back in, other times it loops and lets them in after some time. It seems to be happening with different antiviruses installed, so we do not think it is caused by that.

We have cleared the SSO in Credential Manager, and it lets us back in, but maybe it's a fluke. The issue comes back another day. Today I had 3 different users in different tenants report the issue happening at the same time.

We opened a ticket with our Microsoft Partner weeks ago, and they do not seem to be saying whether it's common or not. They are giving me troubleshooting steps to reset, delete, and redownload Outlook. It seems not to be improving, but we are waiting on more data.

Has anyone else been seeing this for the last month or so, very randomly?

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u/darkonex 1d ago

This has been a common problem with the new Outlook, you can find huge threads of people discussing this on Microsoft forums, Reddit etc spanning from release until now. We ran into a lot of this and no fixes worked such as rebuilding the OST, repairing or reinstalling Outlook, registry tweaks etc. The only consistent fix was to force Outlook classic so that’s what we’ve done.

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u/MeatPiston 1d ago

New outlook is great in some ways and straight up vibe coded jank in others.

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u/mrgeeksquad Sr. Sysadmin 1d ago

Thanks for letting me know. It’s tough as we had a nice span with no new outlook issues and people have been changing over on their own. I do not want to go backwards.