The "invalid HELO name" error typically occur when SMTP authentication is not enabled. Our mail servers require users to log in when sending email in the same way as when receiving email. This is process is called SMTP authentication and is a measure to prevent spam from being relayed through our servers.

To enable SMTP authentication in Microsoft Outlook:

• On the File menu, go to Account Settings and select Add or Remove Accounts.
• Select the email account, and press Change...
• Click the More Settings button, and then go to the Outgoing Server tab. Enable the options "My outgoing server (SMTP_ requires authentication" and "Use same settings as my incoming mail server".

Other email programs have similar options in their settings.