We do not recommend sending your card to a listserv or group email. Paperless Post specializes in personalized mailings, so each recipient has his or her own unique link to the card and reply page. If a card is sent to a single, group email address, everyone on that list will get the same exact card and link.
This will make tracking the emails impossible because you'll only have one email address on the Tracking page. If anyone leaves a note or RSVPs, all recipients who open the card after that person will see the response and can delete or overwrite it.