Messaging Gateway may not be able to download Antispam definitions for some time
The Conduit log may show the following errors:
Error from web server 404 - Not Found : unable to GET: https://aztec.brightmail.com/....
UPDATE: As of October 25th, 2016, the issue has been resolved.
Should the problem still be noticed on certain scenarios, Symantec recommends that all appliance are upgraded to the latest version available.