Apple Mail cannot search mail, is not showing mail in any inboxes or "sent" mailbox

Hello,

I am running Ventura 13.0.1 on my 2022 MacBook Pro, and Apple Mail has become totally unusable.

Search by sender or recipient is no longer possible, and searches do not return any hits even when a message clearly matching the search term is present in the inbox or in one of my sorted mailboxes.

No e-mails appear in either the Exchange or iCloud inbox even when I can clearly see new mail using Outlook with the same accounts.

No e-mails appear in either the Exchange or iCloud "sent" mailbox, even when I just sent an e-mail using Mail and I can see it in the "sent" mailbox if I use Outlook.

I'm ready to abandon Apple Mail entirely, but unfortunately, I can't delete it from my laptop or my iPhone.

In my experience, it has steadily become a truly unreliable email client program.

Any ideas on how to restore functionality?

Thanks