Do you get an error message when you try to send? If so,
right-click on your error message, copy, then paste it into a reply here.
We can't do much troubleshooting without the complete error message.
I have the same problem. The error message I get is :
Subject '', Account: 'pop.omantel.net.om', Server: 'smtp.omantel.net.om',
Protocol: SMTP, Server Response: '250 OK', Port: 25, Secure(SSL): Yes, Server
Error: 250, Error Number: 0x800CCC7D