MT Notifier allows readers to subscribe to a blog, category or entry such that they receive an email notification when a new entry or comment is posted to the blog. Ever since the early versions however, it has been plagued with fake signup problems, spambots and spammers seem to check every box and fill in every field on a page when submitting their spam and hence automatically subscribe to entries, categories or blogs. The double opt-in system that came with Notifier 3.0 definitely helped with this problem, requiring every signup to be confirmed. Although spammers still automatically signed up for notifications, we as blog owners would only ever receive one
Mail Delivery Failed error per sign up (as opposed to one with every attempt at sending notifications as with Notifier 2.x).
In this tutorial, I'll show you several steps to reducing the number of faux-signups. This tutorial was written for MT Notifier 3.4.1 - if you use a different version, some of the code may be different.