I have also seen a module somewhere called "SMTP" which was some kind of C bindings (perhaps?). You could literally get a (resource)/connection with authentication and everything and then iterate over emails.
I use (, ; : -) as I please- instead of learning the English language specification: I decided to learn Scheme and Java;
Would it be easy to spoof an email when I am only looking for 1 type of email from 1 specific sender? Surely I could check ? No?
I will look into paypals own features, I did look into these a while ago before I decided to code my own cart from scratch. A decision I do not regret.
The Paypal IPN notifies your script when a payment is processed. It is VERY easy to spoof that you created the email and to copy the format that was used in the real email. Using email to validate/verify any type of commerce is a BAD idea.