I'm not worried about Google being compromised by a third party. I believe my mail host should not be able to read my email. VPN to a private mail server is goo

I'm not worried about Google being compromised by a third party. I believe my mail host should not be able to read my email. VPN to a private mail server is good, but I dont want to have to trust the mailserver. It might be a bad startup idea if you expect people to pay you 5 bucks a month for an account (may be). But what if it runs like any other mail host, and lives through advertising? Or better still is build on top of one the free vanilla insecure hosts?