As another poster mentioned, you tell your guests your preference when asked. It is a breach of etiquette to mention gifts in writing in your invitation, including mentioning registries. Guests are not obligated to provide a gift, though most do. To give the impression that a gift is expected and how it must be delivered is presumptious. When guests ask about gifts you, your parents or your bridesmaids can tell them where you are registered and mention your preference not to have gifts brought to the wedding. (In some areas, a shower hostess can mention registries in an invitation. In other areas, even that is considered rude.)
Fifty years ago, it was common for gifts to be delivered free to the bride's home by local department stores. Today, that doesn't happen; therefore, guests bring gifts with them to the wedding.
If there will be a substantial cost to mail gifts, you may be limiting what you receive. Guests are not likely to mail a set of pots and pans, for instance, but they may mail a dishtowel or two. Are you thinking about your guests or about your convenience?