I've had similar problems but with aol. However it was necessary to change my outgoing mail, (smtp) to port 587. This still didn't correct my problem but what fixed it was a suggestion from a site member offering a site name that has free downloads to be able to send emails from, it's called a smtp manager. Now my outgoing mail is Smtp.aol.com:587.
The address is:
Http://www.Kelbran.com/products/SmtpMgr.html
The fight with that was only for a few minutes and now I'm up and running. (Being a computer novice that in itself is a miracle.)
It's so sweet!!!
Good luck!!
Susan46