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

I'd bet there is a developer at MS that could find the cause of this in 15 minutes or so if they were to get involved.

I've just just been told there is no further update from the Microsoft Product Group yet which is rather disappointing and I have made my own feelings about that known, even though the impact on my service/users is minimal now.

You might be right, but it could equally be the case that it is so obscure, it is taking time to unearth regardless of who is involved.

It could also be the case that they already know what it is (they certainly know WHEN it happened to within a day) but the change/release control constraints to fix it might be far greater than the incident itself and the current impact. As I've said before on here, this will hit a relative minority of tenants who have no control over the end users/devices accessing their service, and won't hit businesses running Outlook on their corporate desktops as they simply aren't using IMAP. If the fix, or method of fix, poses any risk to the latter, we will likely have to wait for due process to be followed.

Thanks for your continuous effort, Mr Midgley.

Here to add some more info about other users affected.

We created an MS support case 3-4 weeks ago, attaching the code you gave, and still haven't found a solution.

I've seen some peers mention their affected tools, and to point it out, we use Roundcube.

There isn't any modification to the open source code, as we use it to power our Webmail built in a CRM.

Can confirm this Subscribe failed issue is affecting our clients using Oauth2, and it all started around the same time this post emerged and some other people noticed this issue.

As some people of this post have experienced, it is annoying that inside the same client using O365, there are users having the "Subscribe Failed" issue and others, with the same tenant and IMAP settings, continuing their lives fine, with all their folders showing or if they just have selected ones.

This annoys users because they haven't done anything different from their peer.

The affected users are only able to see the Inbox folder.

We are in constant communication with the MS Support team (even tho it bothers us a bit that there is silence for some long days), and it looks like we are moving things finally, as they asked us to record and reproduce the issue while this tool is enabled, linked here (https://aka.ms/SaRA-Assisted). Still waiting a response.

We saw the test connectivity URL you gave (https://testconnectivity.microsoft.com/tests/o365) and tried doing some diagnostics, but still it looks like the affected users are all fine, except they aren't.

Hope my comment can show that this is big enough for MS to move things ASAP.

Best regards,

~Arnau

I agree that MS does give ample notifications, think this problem isn't an intentional break of subscribing rather a change for something else that happens to break it in some cases. A program I developed several years ago got hit with the discontinuing of basic authentication but it was because I'm not in the MS loop. On Oct 6, at 2:34AM the program stopped working. In researching the problem MS had given ample notice and even had a means of extending the basic support for programs such as this if action was taken by the end of September. Thus the problem was 'ME' not MS. And in fairness to MS in the big scheme of things this problem isn't of high severity in my case since there is a work around with Thunderbird rather an annoyance having all the folders visible.

Ian, By my support team, I should have just said Microsoft. I was escalated to level 2 of MS support. I roll my eyes when he says it could not be on the server side. He says he is trying to cover all bases. Ok, I'll go look for your ticket number. Thanks!

-Jonathan

OK - in which case, they need to look at my ticket which is 33661676, and look at the evidence in this thread.

I've just this minute had an update that Microsoft Product Group are currently working on it, and the Microsoft O365 support engineer I have been liaising with is trying to escalate internally for more clarity on what is going on.

On the length of account names, nothing I have noticed. I have a mix of affected and unaffected accounts with similar length, and one affected account that is just four characters.

The way the test script works, is that handles the Oauth2 authentication at the start of the script - and after that, the connection is open/authenticated and it is just sending a series of IMAP commands interactively with the server.

If you look below, this is the Microsoft script running against one of my affected accounts - but in this case, I commented out the last line which does a CLOSE on the IMAP session, and that leaves the session open for me to send my own commands to the server. The two commands with the green arrows are ones I have just shoved in and you can see the LSUB command fails as it did in the script.

So I don't think this is going to be related to authentication.