If you can receive, but cannot send here are the things to check:
- Make sure your SMTP Server is set to mail. before your domain name. e.g. mail.rlmartin.com
- Make sure you have: "My server requires authentication" checked.
- Check your SMTP port settings. Default is 25. Try changing it to 366 and often that fixes the problem. In Outlook, its found under Tools / Email Accounts / Change / More Settings / Advanced.