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

I simply cannot believe it. One month since the initial bug report and no fix yet; shouldn't this be a high priority issue?

The bug hit me just yesterday. Our university had the grandiose idea to switch their email server from a local one to the Microsoft 365 cloud.

Looking at the number of people that are using Linux, or macOS-based operating systems, I'd image that thousands of users are affected by this broken implementation on our campus alone. And we even paid for that mess with taxpayer's money.

You would assume that these things are being tested before they are being deployed on a large scale?! Well done Microsoft, well done...

Morning Ian, can you please share this script you mentioned with us?
I think some of us would like to try it on our own to see if this LSUB command works or not.

You will need to have admin rights on the Azure AD for the affected O365 mailbox/tenant (as I have) - because the script uses an Enterprise Application (PopImap) which the affected account has to be able to access. You then need to obtain the Azure AD Application ID for PopImap and add it into the script.

To be honest, even if you're in a position to do that and then run the script, you're not going to see any more than I have already detailed. It is simply a question of why LSUB commands (regardless of what type of MUA is sending them) work on some O365 mailboxes and not others, even within the same tenant.

An affected mailbox of mine gives the following log file output from the script, which are the same sorts of errors MUAs are reporting:

2022-11-23T08:40:43.3261293+00:00 C 0003 lsub "" *
2022-11-23T08:40:43.3559576+00:00 S 0003 BAD LSUB failed.

2022-11-23T08:40:43.3609600+00:00 C 0004 subscribe inbox
2022-11-23T08:40:43.3898945+00:00 S 0004 BAD SUBSCRIBE failed.

2022-11-23T08:40:43.3938976+00:00 C 0005 lsub "" *
2022-11-23T08:40:43.4234356+00:00 S 0005 BAD LSUB failed.

A mailbox which works (from both Thunderbird and Outlook 2021), also works with the identical Powershell script run against it:

2022-11-23T08:42:53.2989360+00:00 C 0003 lsub "" *
2022-11-23T08:42:53.3674494+00:00 S * LSUB (\HasNoChildren) "/" Trash
* LSUB (\HasNoChildren) "/" Sent
* LSUB (\HasNoChildren \Sent) "/" "Sent Items"
* LSUB (\HasNoChildren \Trash) "/" "Deleted Items"
* LSUB (\HasNoChildren \Drafts) "/" Drafts
* LSUB (\HasNoChildren \Junk) "/" "Junk Email"
* LSUB (\HasNoChildren) "/" Outbox
0003 OK LSUB completed.

2022-11-23T08:42:53.3766586+00:00 C 0004 subscribe inbox
2022-11-23T08:42:53.5378801+00:00 S 0004 OK SUBSCRIBE completed.

2022-11-23T08:42:53.5447857+00:00 C 0005 lsub "" *
2022-11-23T08:42:53.5826269+00:00 S * LSUB (\HasNoChildren) "/" Trash
* LSUB (\HasNoChildren) "/" Sent
* LSUB (\HasNoChildren \Sent) "/" "Sent Items"
* LSUB (\HasNoChildren \Trash) "/" "Deleted Items"
* LSUB (\HasNoChildren \Drafts) "/" Drafts
* LSUB (\HasNoChildren \Junk) "/" "Junk Email"
* LSUB (\HasNoChildren) "/" Outbox
* LSUB (\Marked \HasNoChildren) "/" inbox
0005 OK LSUB completed.

Morning Ian, can you please share this script you mentioned with us?
I think some of us would like to try it on our own to see if this LSUB command works or not.

Morning all. Not much to report yet but I have just been asked to run a test script by Microsoft this morning.

For the non-technical amongst you, this involved a Microsoft product called Powershell running locally on my machine, and the Microsoft script connects to one of my affected mailboxes and issues IMAP commands directly to it. i.e. there is no-ones MUA involved in this test.

It is one particular command - LSUB - that doesn't work on an affected mailbox. That is entirely as expected as this thread shows that some MUA products actually report LSUB as being the problem in the error message they generate.

Conversely, when I run the exact same script (i.e. including the same LSUB commands) against one of my working O365 accounts, the LSUB commands work as expected.

So really, we're just waiting for Microsoft to establish where their problem is.

Have added Vivaldi to my Microsoft ticket as another affected MUA. Thanks.