Problem:
End-users cannot send mail using Outlook
Symptom:
When the user presses the send button, he gets a POP with the error message: 553 sorry, relaying denied from your location [IP address]
Cause:
Un-authenticated connection to SMTP is not allowed on SkyConnect
Solution:
Enable the "My server requires authentication" option in outlook
Refer to the attached screenshot for the Outlook setting.