Intel Mac :: Mail Not Working After Attempt To Send Large File?

So the other day I tried to send a large file through the Mail app to a friend. I realized after clikcing send that the file was indeed too large to send since my Mail froze in the attempt of sending it. I used force quit to get out of Mail and opened it again, and then clicked the x button when it started to send again. But then the message was still in my outbox and in my drafts, and Mail would try to update my inbox and drafts but just continue loading. I went to my outbox to delete the message, and when I did a notification popped up that said "The message could not be moved to the mailbox "Trash—On My Mac". The operation couldn't be completed. File exists". Now whenever I open Mail it's the same story, where it attempts to send the message, and then everything's trying to load but never does.(I went to iCloud recently to send a message, and the only remnant of this action was a draft of the message without the file, which I deleted.)

Info:
iMac, Mac OS X (10.6.8)