Part of it is because its a sympatico email through a Rogers Internet.
The outgoing servers for other ISPs mail servers are normally either blocked or just not routable.
But you can still use that email account.
What you will need to do is use the outgoing Rogers email server, and set it up to use a valid Rogers email account login info in the outgoing validation fields.
****Update****
There are two steps that you need to complete in order to be able to send email using a non-Rogers email account.
1. Your Sympatico e-mail account must be verified and added to your Rogers email account list. ( you need to have a valid Rogers email account ). Follow this link http://www.rogers.com/web/support/Internet/webmail/279 for details on how to complete this process.
2. Use smtp.broadband.rogers.com as outgoing server. On the Outgoing Server Tab check "My outgoing server (SMTP) requires authentication" and select "Log on using" : enter your Rogers email address and its password. On the Advanced Tab change the Outgoing server port to 465 and "Use the following type of encrypted connection: SSL ".
You should be able to send messages now.