Horizon sells the boxes. I don't know their website off hand, but you can google it, I'm sure. I know that others have been approved, but I couldn't find on the PO site which they were yet.
You have to use one of the approved boxes. The company that sells them gives you a weight on the box. Guesstimate the weight of your birds, then include about 3 pounds for shavings or hay at the bottom and some apples or cukes at the bottom. You'll need to put those things in for the birds.
After you have them boxed according to the manufacture's instructions and have included something to keep them hydrated (apples or cukes), then take 'em to the Po and ship them via express mail. There are a very few limited zip codes any more, but you should check with your PO before taking your birds down to make sure you aren't trying to ship to one of them.
You can do the whole estimate thing online by the way at
www.usps.com and use the weight with express shipping.
You can NOT insure live birds, unfortunately. They do guarantee a time they should get there though and you'll know that before you leave the PO. Keep your receipt so you can send the number on it to the person buying them so they can track them on their trip.
I guess that's about it. Just make sure you're shipping non-buggy, healthy birds and wait as long in the day as you can to take them down, unless your PO has more than one truck going out during the day, then get them on the earliest one.
Stacy