Mail Unread count always wrong and getting worst day after day since 2 weeks

Hi!

The Apple Mail.app client is really giving no better results or counts in all my smart mailboxes, suddenly … with no explanations or any particular upgrade/installation.

At this point, and as it is shown above, it says I have 5 messages, but counting says 82 unread, and there are only 4 messages really unread listed. It is an example, but other smart mailboxes miscount e-mails or even give wrong results recently!

To get back a working e-mail application, I tried several times those 2 weeks to :

1. Remove Envelope files
2. Rebuild mailboxes (all)
3. Rebuild Spotlight index
4. Delete old messages and archive some…
5. and again, and again …

It is getting worse each time.

I'm out of steps to find a solution.

Should I totally remove the Mail folder in Library?

Of course, changing or remove SmartMailboxes items will not affect the behavior. Even a light basic one fails.

I have to say that it is a Microsoft Office 365 Pro e-mail account, and of course, I validated that with Microsoft Outlook 16.72, there are no such as 82 unread messages. The server side is clean! But I want to keep using Mail.app…

The trouble is located on Mail.app client (Version 16.0 (3731.500.231)).

I'm on latest Ventura 13.3.1 (22E261) version.

Thanks!