@quanticle - There's a balance to be had there. Yes, being continually emailed by a service you had no interest in is a terrible idea. But we've found that people drop off for other reasons - technical issues, walked away and forgot, or had unanswered questions. An easily-ignorable one-time e-mail is harmless
My opinion would be that if you're getting a lot of these kinds of issues, the signup page could well be the culprit.
A much better solution is to have 2 boxes "Email address", "password" and a button to make it Go.
If you need "inside leg measurement", "first pet's tail fur colour", "crazy aunt petunia's whisker count at last birthday", you can ask for that as part of the natural flow of using your service later.
Get people in and using it, make it really clear before they click the signup button what the primary benefit of your service is.
