Accessible URL Only From Email

[amax]

Hi All,
I wish to include a link to download a PDF from within an email once all users register on my site e.g.

Thank-you for registering. You can download the PDF by clicking here / or by viewing http://www.mysite.com/pdf/mypdf.pdf

I have all the registration / email functionality built etc but have no idea how to actually mask this URL so that someone cant browse directly to http://www.mysite.com/pdf/mypdf.pdf or forward the link on. It should only be accessibly from the email.

Is this possible to do and if so what functions should I be looking at and reading up on. I would love some advice on how to go about this or any thing that may help point me in the right direction to learn how to do this

[NogDog]

I can't think of any way to tell if it's from an email: to the server a HTTP request is a HTTP request regardless of where the user clicks on it. All I can suggest is including a query string parameter with a unique value, and limiting the number of downloads that can be attempted for a given value. (You might want to make it a small number rather than just 1, in case a legitimate request aborts and has to be re-tried.)

[dagon]

another option similar to the above send them a one shot username\password and link to a page that sends the pdf, store the pdf outside the web root so it cant be found by mistake.