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
    2022-12-05T13:04:10+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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  2. 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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  3. Anonymous
    2022-12-05T12:22:00+00:00

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

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  4. Anonymous
    2022-12-05T11:45:05+00:00

    The only clear and verified pattern I have actually seen to this is the one I noted early on in this thread and fed back to Microsoft. i.e.

    My AFFECTED accounts were all being accessed via IMAP at the time the fault materialised.

    My WORKING accounts* had never been accessed with IMAP before, and were added to mail clients AFTER the fault materialised by way of testing.

    I have three different O365 accounts, and I have been using all three with IMAP & OAuth2 (Thunderbird on Linux) for over a year. Now two of them are affected by this issue, while the third one is still working fine. No idea what the difference is between the working account and the affected ones.

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  5. Anonymous
    2022-12-04T23:36:36+00:00

    Thank you for clarifying.

    Seeing that the server response is the same for affected and unaffected accounts, this points towards an account-specific configuration file issue, doesn't it?

    I am not sure how this is implemented on the server side though.

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