Whether or not you send out invitations for the rehearsal dinner depends largely on the number of people invited. If you’re planning an informal gathering with just your wedding party and immediate family, you may not need to mail invitations. However, if you’re having a large dinner with many out-of-town guests, invites will help you keep an accurate head count and stay organized. Traditional paper invitations or postcards may be used, but an electronic invite is acceptable as well.