Without going into great detail, customers will use my web site to process documents. Once processed I'd like to make a document available only to the particular customer who provided it, as a monthly paid subscriber.

Is there any way to make downloadable files available to customers, through a program automatically and securely?

In other words, Customer A's document is processed and is sent to a folder only he can access via an automatically emailed link.

Customer B's document is processed and is sent to a folder only she can access via an aoutmatically emailed link.

etc.

Any assistance will be appreciated.