Qwitter e-mails you when someone stops following you on Twitter with a message . When someone stops following you on twitter, Qwitter sends an email to you which you mentioned in the Qwitter.For this you have to submit the Twitter username you want to track and your e-mail address.This is really helpful service to track your followers.
This may be useless for Twitter users who have hundred and thousands of followers, but for small users who have only a hundred or a few hundred followers – this is a valuable service. Now you can finally know what your followers are doing.
Link : Qwitter