To fix this problem when sending mail from Outlook Express:
1. Open Outlook Express, and click Tools
2. Click on Accounts
3. Click on the email account that you have an issue with and then click Properties
4. Click Advanced
5. On this screen remove the checks from the boxes This server requires a secure connection for both Outgoing mail (SMTP) and Incoming mail (POP3).

To fix this problem when sending mail from Microsoft Outlook:
1. Open Microsoft Outlook and click Tools
2. Click on Email Accounts
3. Choose "View or change exisitng e-mail accounts" and click Next
4. Highlight the email account that you have an issue with and click Change
5. Click More Settings
6. Choose the Outgoing Server Tab and check "My outgoing server (SMTP) requires authentication."
7. Choose "Use same settings as my incoming mail server."
8. Click OK, Click Next