I'm not familiarised with Exchange, but since nobody has replied so far, not sure why, let's see whether I may help… and learn something new along the way… :)

My understanding is that Exchange mail should be fully accessible with IMAP. You may have to enable (and configure) IMAP in Exchange first, though. I assume you already knew that and that's not the problem…

What do you mean this is a known issue? Do you have a reference for that? A quick search would seem to indicate that accessing Exchange mail with IMAP using Thunderbird should work reasonably well…

In Thunderbird, right-click on the account in the folder pane and choose Subscribe. Do the missing folders appear there? Do they appear ticked or not ticked? Select the ones you want to appear in Thunderbird, click the Subscribe button, then OK, and see whether that solves the problem.

Thanks David,

A number of employers block IMAP access for security reasons. They only allow Exchange access.

I asked copilot : "There are missing folders in thunderbird when syncing with a microsoft outlook account. Do you know when this problem was reported for the first time?"

Its reply was: "The issue of missing folders in Thunderbird when syncing with a Microsoft Outlook account was first reported on January 20, 2016. Users noticed that only the 'Inbox' and 'Trash' folders were visible, while other folders were not being displayed. Another significant report of a similar issue occurred on August 6, 2021."

Copilot suggests some solutions, but they don't work. The only real solution is to use the Owl extension for Thunderbird.

I thank Owl for being there, but at the same time, as I am new, I see that the extensions are not all of the same level. I trusted Owl enough to install it. But I see that Thunderbird does not seem as complete as "Outlook" without using extensions. My problem is that I have fears about some extensions.

Honestly, I would love to completely replace Microsoft Outlook with Thunderbird. However, the path does not seem as easy as expected, especially for some details, such as the fact that you can only have one signature (I saw that extensions exist, which brings me back to my previous paragraph).

Is the development of Thunderbird regular (I made a donation hoping to help a little)?

How much can I trust the extensions?

Thank you very much for taking the time to reply to me and I wish you a great day.

Ah! I see. Well, the following article has a "How to stay informed" section you may want to check then:

https://wiki.mozilla.org/Thunderbird:Exchange