How MailChimp forms work
If you use a form from MailChimp it allows the user to enter his First and Last name and his email. You can even add custom fields to it. The problem is that after you enter your email you have to confirm it in your mailbox. And this is the step which most of the users don’t do.
What I do
I do a very simple thing. I have a signup form from MailChimp and I use it to gather user emails and validate my idea. I log the entered email every time the user clicks the Submit button in Google Analytics and then send it to MailChimp.
I have 140 emails confirmed. And 240 in the analytics. WOW! This makes me think there is a major problem with the confirmation email. I plan on importing the analytics emails into the MailChimp list.
I think that the biggest problem is that users signup from the website in Bulgarian and the email they receive is in English. I will do it in Bulgarian and check again the results!