Answer

PROBLEM

From the AutoUpdate log:

response URI: https://update.gfi.com/license/gfi.key
Content-Length: 0
error: unexpected ContentType: text/html; charset=ISO-8859-1
error: StatusCode: 200

ENVIRONMENT

• GFI MailEssentials 
• All supported environments

SOLUTION

Confirm the license key is correct in both databases (no extra spaces or old licenses listed)

CAUSE

This is caused by problems authenticating the license key.