Did you check the option 'scan Outbound Mail' into Internet Mail provider settings?
Do you use SMTP authentication? (I mean, one smtp server to connect the Internet and another provider - or smtp server - into your email address? If so, check smtp authentication, write only
#yourserveraddress (changing to the real address...), let the password in blank (or fill it correctly) and check for save this password.
Can you do that? Need more help?