Getting Mail in the USA
You can have mail or a parcel delivered to a post office in the USA, General Delivery, and they will hold it for you for 30 days, no charge (2010). All you need to know is the city, state, and zip code of the post office where you will be cruising to within the next 30 days and have the sender address the package as follows:
City, State, ZIP Code
We tried this when we ordered a needed part for our boat from Defender Industries while in Annapolis, MD. and had them send it, as above, to the post office in Oriental, NC. where we knew we would be sailing to within the next couple of weeks. It worked like a charm!