Ok that's 2 customers who are also HNers. I think you'd need to do better than that. We are hardly a representative of the general consumer.
There is another problem, US govt' need to get access all these messages. For example http://en.wikipedia.org/wiki/Hushmail, people seemed to have signed up, but Hushmail was forced to provide plaintext messages to US govt upon request. So they sort of compromised their main selling point.
That is probably the largest problem, you'd be stuck between a rock and a hard place. You either please your security conscious customers or please Uncle Sam. You can't please both.
It doesn't have to, but unless it is located in Iran, NK or other US-unfriendly place, US govt can always pressure the local govt to pressure the local business to turn things over. I wouldn't, for example, count on countries like Switzerland, US is already getting to its banks to turn over US accounts, and is supposed to be one of the most independent and un-influenced countries.
With the current legislation trend, eventually un-cooperative or "terrorist friendly" sites would just be filtered out and blocked, so you might have a hard time accessing your email. Some messages might never make it to you.
I was actually talking about writing a front-end that you could host on your own server, not a gmail clone. (I wish I could update my original comment.)
There is another problem, US govt' need to get access all these messages. For example http://en.wikipedia.org/wiki/Hushmail, people seemed to have signed up, but Hushmail was forced to provide plaintext messages to US govt upon request. So they sort of compromised their main selling point.
That is probably the largest problem, you'd be stuck between a rock and a hard place. You either please your security conscious customers or please Uncle Sam. You can't please both.