Paypal Automatic Message after someone buys?

I've done a lil research and yes it can be done with some program via the IPN which, I believe, is only available on higher accounts.

If you only have a few codes, I think manually processing is probably going to be the easiest. You can make a simple form email and just insert the code once you get a email from paypal sayin someone paid. Place a lil notice on your site that says customer will receive email with product key within X amount of time after payment is received....something like that.

Sorry, I couldn't be of more help. If you do need someone to program it for you though, let me know. Keep in mind automated emails will have the same code. You can with some programing send out a new "custom" email to each purchase.

Simply put it can be done, it takes some special coding with Paypals APN so it's not as simple as pushing a button or making a few clicks.

I'm not sure, but I think that if they are logged in it will send them and email anyway, and I think if they are not logged in, it will ask for their email when they buy and also email them the information

I believe that is an option with business paypal accounts, if I remember correctly. You however, redirect them back to a "thank you" page, but that is going to be the same page for everyone and not exactly what you are looking for in terms of product key.