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
    2022-11-09T20:55:54+00:00

    All - my latest test findings as follows:

    I took the decision today to run the diagnostic to temporarily re-enable IMAP/basic auth on my tenant (this gives system admins a bit of extra time if they were caught out by the basic auth deprecation), and see if the fault is still there with an affected account reconfigured back to basic auth.

    Findings as follows:

    1. It doesn't make the slightest bit of difference to the fault - an affected account remains broken for subscription. So this doesn't appear to have any connection with the basic auth change/setting. This is what I expected if I'm honest as the change hit my tenant early in Oct and this problem didn't appear until a few days back.
    2. Because my tenant accepts basic auth now, I was able to add an affected account as type IMAP to Outlook 2021 on my test machine and that gives the Outlook error "The folder list was not fully refreshed. An IMAP command failed" when I tried to query IMAP folders. Ticking the equivalent box to TB to display all folders works in Outlook too. I then added one of my known working accounts to Outlook as IMAP, and subscription works fine on that.

    So, what this proves in summary is the fault presents itself the same in both Outlook 2021 and Thunderbird and the fault is sticking rigidly to the affected accounts. So it rather looks like the problem is at the O365 end on a number of tenants.

    I have updated the ticket I have open with Microsoft for the fault on my tenant.

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  2. Anonymous
    2022-11-10T03:11:55+00:00

    Great detective work! Thanks. Now there's hope of a MS 'fix'.

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  3. Anonymous
    2022-11-14T08:56:24+00:00

    Any news on this ? It's been 2 weeks with this issue and it's getting frustrating...

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  4. Anonymous
    2022-11-14T12:55:03+00:00

    I've just chased Microsoft on the back of my support ticket, but I'm not expecting a rapid resolution to it, given there is a workaround available to display all folders.

    Remember too that the number of users and O365 tenants affected is going to be a small percentage of the overall O365 service - simply because most corporate users of O365 will have users on Outlook accessing with the standard Microsoft connection protocol MAPI, and not IMAP. None of my Outlook users are affected by this issue for that very reason - and it was Thunderbird using IMAP where the problem first surfaced for me.

    All I can suggest is those of you who manage O365 tenants open your own support ticket in Admin Centre so Microsoft can at least see who is affected. By all means cross-refer to mine which is ticket ref. 33661676

    If you are an end user and certain you are seeing this exact same issue, then maybe contact your service desk/O365 sys admin and ask them to do the same.

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  5. Anonymous
    2022-11-15T10:55:52+00:00

    Seems like this was just fixed (at least for me). The only other thing I did before I finally got my folders back was starting Thunderbird with debug-output to better investigate the problem and having it running in the background for a few minutes.

    MOZ_LOG=IMAP:4 thunderbird

    P.s: Nothing fixed here - I just accidentally activated the workaround (see Mark Nagle's Post from December 4.).

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