outgoing messages not going out

I sent a couple of emails that were oviously too large.  There were several pictures. Now I Keep getting the box that says "sending 1 of 6 emails"  then it fails .  When I close out of my email it says "you have messages in your outbox do you want to send" I say yes but it fails again.  I can't send emails out because these are tried first and then fail.  When I go into my outbox to delete them there is nothing in the outbox that shows. Pleases help.