On our general donation form, we need the option to have donors choose to make a tribute gift and send notification by email OR mail. On other donation forms, we have just the option to send an email notification. Also need NXT to have the capability of sending eCards for email notifications like in LO.
Requiring mailing address for tribute notifications will only create friction for potential donors. It's too easy to imagine scenarios where the donor may not have address information available, leading them to delay making a gift indefinitely.