Help mail app is freezing up my whole computer

Help, I tried to send an email a few days ago which I now know was to large. The problem is it is sitting in my outbox causing the whole computer to freeze up. I’ve deleted the email from the outbox but on the side of the screen it still says there is 1 email in the outbox folder and at the bottom of the screen it says sending message.

im super frustrated as I’ve tried turning the computer off, force closing the mail app, even deleting the file I was trying to send off the computer but the instant I restart mail app the computer starts to crash again.

currently running masOS Majave. 10.14