Most outgoing email problems are because 'SMTP authentication' is not enabled in the email program. It needs to be enabled to send the email.

Here are the instructions if you're using Outlook.

1. Select Services on the Outlook Tools menu, which opens the email Services window.
2. Highlight the Internet E-mail account, and click the Properties button to show the settings.
3. Click the Servers tab, which shows you all the mail server settings.
4. In the Outgoing Mail Server section, make sure the 'My server requires authentication' checkbox is checked.