I feel like an idiot asking this, but can anyone out there explain to me what exactly a "return receipt" is? I understand it has something to do with receiving a confirmation that the recipients of the email actually received it. If this is in fact what it is, I think it'd be quite useful when it comes to debugging (I am working on a mailing list manager right now). Is there any kind of header that you can add to an email to accomplish this or, otherwise, is there a hard coding way?
Any Help Is Appreciated.