- Error message: "HTTP Error - 405" - Looking at the Mail Security Installation on the server in question (in our case), the server was actually running version 6.0 and included anti-spam. For some reason, the 4.6 MMC was left installed and whenever and admin actually tried to assert a setting using the old MMC, this event id and error was logged. To correctly administer the product, the new MMC should to be used.