G-mail app email is not sent "Error" in red font why?

Hello

I tried to send an email using the G-Mail app, but it's stuck in the outbox with the word "Error" written on it in red.

Other emails were usually stuck there only because of a lack of storage space and it always just said "queue" and not "error".

And they were always sent when I deleted the data from the Google Play Services app.

But that didn't work in this case.

How can I check what exactly the error is that was noticed?

Ps I can't find the Google Mail app as a topic name