Why is this not sending any of my emails that have attachments?

I have tried several tests. When I send a test message without an attachment, it works. However, when I attach anything it never goes anyplace. It does not give me an error message. I does not show in the sent items. Nothing. Only when I close the program, it says “You have 7 messages not sent. Do I really want to close the application?”
I have ads to publish in newspapers, send to clients, etc. This is not working for me.


how big are those attachments and what provider do you use? For example Google will not allow you to send anything above 25MB.