Unable to subscribe to Office 365 IMAP folders from MUA since 2022-11-01

Anonymous
2022-11-02T07:33:01+00:00

I'm using Thunderbird to access my Office 365 mail account and it has been working fine (a couple of month ago I also switched to OAuth2 due to deprecation of basic IMAP authentication). However, since 2022-11-01, Thunderbird is unable to subscribe to IMAP folders. Last time I know it was working was last Friday 2022-10-28. Thunderbird is able to list to available folders (e.g. when opening the "Subscribe" dialog from the mail account settings), but cannot subscribe to them. I enabled IMAP logging in Thunderbird, and it shows that the server answer the subscribe request with "BAD SUBSCRIBE".

It is not a password/authentication issue, as Thunderbird can still see the content of "Inbox" and "Deleted Items". And if I disable the option "Show only subscribed folders", it can access everything in my Office 265 account.

Edit: here's the relevant logs from Thunderbird (note: I've replaced the actual folder name with "xxxx"):

[Parent ...: IMAP]: I/IMAP ...:outlook.office365.com:A:SendData: 76 subscribe "INBOX/xxxx"

[Parent ...: IMAP]: I/IMAP ...:outlook.office365.com:A:CreateNewLineFromSocket: 76 BAD SUBSCRIBE failed.
Microsoft 365 and Office | Subscription, account, billing | For business | Other

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  1. Anonymous
    2022-12-05T12:49:07+00:00

    Not a situation I've personally seen. Are all three accounts on the same tenant just out of curiosity?

    No, three different tenants. (I work as a consultant and these are three different clients.)

    I have no admin access to any of these, so it is limited what I can check / test. The accounts are (were) set up with the same parameters on my side.

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  2. Anonymous
    2022-12-05T13:04:10+00:00

    Hi,

    I just wanted to add that also the email accounts of a prominent Italian University, Bologna University, are affected by this.

    I hope it will be fixed soon.

    Thanks to the community for the workaround :)

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  3. Anonymous
    2022-12-05T13:16:40+00:00

    Same here, at a Swiss University. Not all IMAP users are affected. Case opened @MS referencing ticket #33661676. Let's hope they fix this soon.

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  4. Anonymous
    2022-12-05T15:09:47+00:00

    I have three accounts on the same tenant subscribe works for one of them and fails on the other two. The one that works is a test account and is seldom used while the other two are active every day. I don't have admin rights thus have limited visibility to settings.

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  5. Anonymous
    2022-12-05T18:25:37+00:00

    **************** EDITED DUE TO A TESTING ERROR ****************

    This and other feedback prompted me to do a bit more testing of my own this afternoon.

    I added a new account to my tenant today to see how that behaved. That account WORKS in both Thunderbird, and using the Microsoft testing script.

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