According to MAPS Guidelines:
Permission of new subscribers must be fully verified before mailings commence. This is usually accomplished by means of an email message sent to the subscriber to which s/he must reply, or containing a URL which s/he must visit, in order to complete the subscription. However it is implemented, a fundamental requirement of all lists is for verification of all new subscriptions.
This "Plugin" will not only manage your confirmation emails for you but also hold a copy of the subscribers response email should you ever need to publicly confirm this.