I think I answered your question in a separate email, but for the benefit of others who may ask I am pasting my reply:
I am aware of this issue and it’s a very frustrating circumstance! The Sunlight Foundation gives you an immense amount of data to work with, but only 20 or so members of Congress offer their email address.
Unfortunately this is intentional on the part of Congress — crying “spam” and out of concern for fraudulent communications most members of Congress opted a few years ago to discontinue their direct email addresses in favor of web-based forms. As you can imagine, this is incredibly frustrating and has made it more difficult for many constituents to communicate with their representatives. The forms they use are not standardized, so they are not easy to parse, and some require extensive amounts of information or CAPTCHAs, further reducing completion rate. There are several service providers out there that either attempt to parse forms or fax messages to congressional officials (the big ones are: Convio, Democracy In Action, Blackbaud Sphere and Capwiz), but they all have their drawbacks, and depending upon your volume they may charge thousands or tens of thousands of dollars annually.
A free and open source solution may be forthcoming though, and hopefully will become part of WPCongress ??