Is it possible to configure an IMAP account in Thunderbird with a different domain on the address and the server?

Question

I have an email address provided and managed by OVH (French ISP)

I'm trying to configure the account in Thunderbird (which I've been using with multiple accounts, including Gmail over IMAP, for years with great satisfaction). It's version 91.8.0 in Debian 11.3. No fancy tweaking or whatever.

I followed the instruction from my ISP (https://docs.ovh.com/fr/emails/configuration-email-configuration-pour-thunderbird/) - ok, it's a guide for the windows version, but that shouldn't be an issue.

The thing is, my address is like [email protected], but the mail server is ssl0.ovh.net.

I'm sure the password is correct, but when I go and validate the settings, Thunderbird tries to check the password, and it gets stuck there.

I noticed in the status bar that Thunderbird is actually trying to reach [email protected]@ssl0.ovh.net... That must be (part of) the issue.

I tried to go to Advanced settings (so it creates the accounts and sends me to the account settings page), and there Thunderbird changes the actual server (which should be ssl0.ovh.net) to the email account's domain (somedomain.fr in my example)... Ain't that weird ? (also, it seems not to be able to determine the server type which remains empty, and most dropdown options, like authentication methods, are empty, or rather there are no labels).

Has anyone ever run into such an issue, and better yet, solved it ;-) ?

(not sure if the cross-domain tag is relevant)

Edit 2022-05-03 : After many tests, still not working, but I have dug a little deeper.

I've set up the account manually with "Advanced configuration" so it doesn't try to check the password.

In the Folders panel, the account has no name and only a sub-folder named INBOX. When I try to browse this INBOX folder, I get an error :

Unable to open the summary file for INBOX on [email protected]. Perhaps there was an error on disk, or the full path is too long.

Running Thunderbird in full debug mode from CLI :

thunderbird --safe-mode --jsconsole --verbose

In the shell, from the verbose mode, I get this error repeatedly :

IPDL protocol error: Handler returned error code!

###!!! [Parent][DispatchAsyncMessage] Error: PClientManager::Msg_ForgetFutureClientSource Processing error: message was deserialized, but the handler returned false (indicating failure)

But I don't think this is related to my problem.

However in the JS console, I get an interesting message :

gloda.index_msg: Problem entering folder: INBOX, skipping. Error was: undefined:659: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIMsgFolder.msgDatabase]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: resource:///modules/gloda/IndexMsg.jsm :: _indexerEnterFolder :: line 659"  data: no]

Now, where do I go from here ?