When we started considering the matter of a consolidated thank-you emails, we realized that simply appending various products' thank-you emails together consecutively into one big message could be too confusing for many buyers, so we went with a different approach to offer a single thank-you email:
In your Seller Admin > Account Preferences, you can now specify a Common Thank-you Email Subject and Message which would be sent to the buyer just once for each entire order. You can also Enable Templated Email there and use any of our order-specific email template [%variables%]. The Common Thank-you Email cannot include any item-specific data, so you can use the [%thankyou_link%] template variable to insert a link to the thank-you page, where item-specific data can appear. Printing the thank-you page may also suffice as a packing slip, especially since you can use template variables to format the thank-you page however and with whatever information you may wish. You can now view the thank-you page for any order directly by viewing your Transaction Log and clicking the order's Transaction ID.
Note that the Common Thank-you Email is a separate message sent in addition to any item-specific thank-you emails you have configured, unless you also disable the individual thank-you emails for each product. Tangible goods would normally issue no thank-you email of their own at all unless you had entered something in their Email Message fields, so you can just leave that field blank to disable a tangible product's individual email. For any digital product, you would also want to check Enable Templated Email while leaving the Email Message field blank to disable that product's individual email -- in that case, you should also Enable Templated Email for the Common Thank-you Email and insert the [%thankyou_url%] variable somewhere to provide a link to the thank-you/download page.
A sensible approach to templating a Common Thank-you Email might start with presenting basic info like so:
==========
Subject: Your [%business_name%] purchase
--
Dear [%first_name%],
Thanks for your purchase. Your can view your order details at:
[%thankyou_link%]
{add'l info/instructions/offers would go here}
Sincerely,
[%business_name%]
==========
EDIT: Corrected template variable to insert Thank-you Page link.
