Mail app sending emails into the void

Dear all!

Two days ago on Monday the 24th around noon (any recent update coming out at that moment?) my Apple Mail application stopped functioning properly.

Whenever I send an email, I receive a notification that everything went well, but neither are my emails received anywhere nor (and that's even worse) are my emails stored in the usual Sent folder. Effectively, once sent, my emails are going into the void and I don't see any traces of them on my computer (2020 Air, Ventura 13.5) anymore.

I still receive my emails (I have three different accounts, Gmail one of them), I just can't send any emails anymore from my mail application. If I send something from the gmail website, my Mail app will show them in the Sent folders (and receive them, in case I send a message to one of my accounts).

I've never seen a problem like this. There's no error sign whatsoever, just no trace of any sent messages..

Obviously, I haven't changed any parameters or settings (at least not knowingly) in the last couple of days and I can't find any sort of error messages or signs of things not working properly...

Any help would be greatly appreciated!