How to get emails back from VCs

I've been approaching a select group of VCs, via cold email, and sometimes I get a response - sometimes I don't. My "social marketplace for contracts" startup (ContractIt) is going swell. We have a 13 person team, our product is being iterated and tested and we've been able to get valuable feedback.

I want to be taken seriously, and even if we're "too early" because we haven't launched yet - it's nice to begin conversations with these people. Perhaps I should be attempting to build a remote network, instead of going in cold.

Any tips?