Marketpress custom auto-reply based on product

Is there any way to create a customized email receipt based on which product is purchased? One of my products enables access to password-protected files, and we are currently having to manually email the access info to each purchaser.

(This product can't be configured as a digital download, as I don't want a separate "my account" for each customer -- the file links need to be mixed on a page that includes non-protected links, and the access details are the same for all users.)

It would be great if the access information could be included in the automatically generated receipt. Any solutions/suggestions for this?