I have sent several via Funky Pigeon which I believe is a subsidiary of W. H. Smith. You pick your card from the assortment they have on line (quite a lot) and write your message in them. This is quite easy, the pages turn over for you. Very clever! Then you put the details of where you want the card to be sent and your own details including your credit card number and when you want the card to arrive. The cost of postage is included in the price of the card so that it seems as if you are getting the postage free (not very likely). It is more expensive, I reckon, than going to the Card Market and sending it yourself, although very convenient if you cannot get to a shop. Personally I think the cards are not so good, but there you are, if you have no alternative, it's okay. So they do not have to have an email address - it's just ordinary mail.