[emmelaich]

> There is no tool available to me to understand

I _think_ this is because G doesn't want people gaming the system.

> or correct the "problem".

I regularly fish mail from my spam bin. From mailing lists, and other important stuff -- and indeed Google's own mail!

One thing you can do is to get people to add you to their contacts list.

It's a hard problem. There is one "solution" you probably do not want. Have Google (and other companies) give their imprimatur to certain mail senders.