You're right -- it was a big issue for folks, which is why I ended up scrapping it in lieu of the new process:

- you get the project email and click "learn more" - that takes you to a page w/ details and an "i'm interested" button - clicking that button tells the project owner - the project owner then chooses to initiate contact further (which is why it's helpful to have a URL on your account.) - that is what sends the first email

It was intended to both cut down on project owner email overload as well as fix the confusion around what exactly happens.

Also, I plan to let folks attach a blurb of text as to -why- they're interested in a project. Should be an interesting experiment.