It is really up to you. If you wish to be contacted back, it might be a good idea to write your address on the postcard. However, not all postcrossers will write you back.

Members frequently ask why their address is not sent automatically to the person who registers the received postcard. The reason is that some members are not comfortable with this. It is their choice if they would like to send an address on the postcard; we will not do any different.

Note that when you register a postcard, you can leave a message. At this point, you can request the address of the member that sent you a postcard if you would like to send a return postcard.