Verified answer

I'm not sure what you're asking, but if you sent an email to a non-existent address then just delete it from your 'sent' box. Sometimes the sendee's host server doesn't accept the message for some reason (switched off; thinks it's spam; puts it in a queue) so it gets bounced back with a similar message. In which case try sending it again. Sometimes you may inadvertently mistype the address.

Or if you want to unsend, usually you can't, unless you are an AOL subscriber sending to another AOL subscriber.