Configure the forward has one bold minus.
One of the factors which Gmail detects spam ip address of the sender.
Sending letters is killing this factor, all emails sent from the ip address of the host. As a result, the quality of the recognition of spam drops dramatically.
Headers with ip addresses of senders that you add to the hosting companies, Gmail does not trust because of spammers, no one bothers to add any headers.
While using the paid Google apps has the option to trust the listed hosts. But is it worth to pay for that in the chain there was an extra weak link? Gmail is obviously safer than most homegrown hosters.
The solution is to attach a GoogleApps domain, and all.
Headers with himself, of course, Gmail does...