Return address printing is not currently on promotion, so it isn't discounted.
Most of our printed envelope options have a fee associated with them due to the additional cost to us to add the service. Printed, stamped, and mailed envelopes along with return address only envelopes will have an additional charge for the service, but we have decided to offer recipient printing for free (for basic designs) as a way of rewarding customers who utilize our Address Book. Uploading addresses to your Address Book allows you to organize your mailing list and also makes your mailing process more convenient for any future orders, so this is part of how we are promoting the service and it's currently free of charge.
If you have further questions, feel free to contact us.