Updating Return Addresses
As long as your job hasn't been paid for, you can still update the return address for your mailing (if the mailing is in your shopping cart you'll first need remove it from your shopping cart).
To update the return address, click on the mailing in question and it will take you to the recipient list/review page. At the top on this page, you will see a light blue box above the recipient list that will give you an option that says Update Return Address. Click that and you will be able to change your return address for that mailing.
Keep in mind, you are able to make any changes to your mailings if they have not entered your shopping cart. Once you place a job into your shopping cart, you will not be able to modify it. At that point you will need to delete the mailing and re-upload it.