What folder in File System (Mate 16.4) is the unsent mail held in? It's now up to 21 unsent

THERE ARE 120 PEOPLE WHO THIS IS SENT TO AND NOT ONE OF YOU CAN HELP?
JEEZ, WHAT A WASTE. THANKS A*S-HOLES.

 I now have 21 e-mails that are not being sent for a multiple of reasons (though the send tp addresses ARE valid, I've used them on another computer).

There is now a long list of unsent mail in an error message "Error While Sending Message" that appears after "sending and receiving" mail:
I want to purge these unsent messages from the Send mail queue (or corrct whatever is "wrong" in the send-to address) but I can't find any Evolutuon folder or any "Mail" folder, or anything that might contain these unsent messages anywhere in my File System.

And no messages are being held in any of the Outbox folders for any of my e-mail accounts (and no messages EVER appear in the Outboxes) in the program so I can't just delete those 21 e-mails. But they have to be being held SOMEWHERE.

I have searched high and low for an Evolutuion folder in my File System but there isn't one! How is that even possible since Evoloution is installed and is otherwise functioning?

Most often my mail sends and receives messages just fine, but these 21 unsent messages just won't send for various reasons. And I have no way to correct the supposed "syntax errors" (or any of the other perceived errors) since I cannot find these messages anywhere on my computer.