David, first thing you need to do is determine if the state in which you live has quarantines regarding citrus being shipped. And you also need to find out if the state in which your friend resides has a block against citrus from any other state.

You might find that info at your local post office.

Thanks rhizo thats useful info i would never have thought of that. Still have no idea how to keep it fresh in a package though.

I send cuttings often. Not citrus in particular but I do anything that could wilt the same way. Wrap the cut end in a damp-not-drippy paper towel, put a sandwich bag over that & gently twist it closed enough around the stem just enough so the towel doesn't dry leaving a minor gap for some fresh air, a little piece of tape on the plastic, not the plant, so it doesn't unroll. Then you can slip the whole thing into a TP or paper towel roll to keep it straight if it's small enough, or loosely rolled in newspaper if bigger. Then put in the smallest possible box with crumpled paper (or pack more cuttings) to fill the empty space.

USPS has flat-rate boxes in several sizes, especially handy if one needs to know the cost up front, and tube-shaped boxes that can be handy for cuttings.

It's a pretty hot time of year, waiting until it's a little cooler might be prudent.

David- r u sending as budwood for grafts in which case u dont need any leaves just the stems or will your friend try to root the cutting where better to keep a few leaves . Like Tiffany suggested , spray a kitchen towel , wrap the cuttings with it and then put in in a ziplock bag . Alternately u can go all out buy water tubes that florists use n stick each stem then put in ziplock.