Un-tick the ‘This server requires authentication’ option.
This however may leave your correspondence vulnerable. Turning off the SSL encryption requirement.
If you want to disable it, there are 2 ways. We suggest to leave it since the warning only appears when you restart your Outlook and send out email. When you send a secure message in Microsoft Outlook 2013, Microsoft Outlook 2010, Microsoft Office Outlook 2007, Microsoft Office Outlook 2003, Microsoft Outlook 2002, or in Microsoft Outlook 2000, you may need to use a SSL certificate that does not match your e-mail address.
