Well, im not really sure? I think you like wrap each eggs in like news paper and put them in a oversized egg carton, and make sure they are wraped REALLY good, and them I think you take them to the post office? But im not sure where you take them? I know that thats how you wrap them though. Please correct me if im wrong.
There are many different ways to successfuly package eggs. Using a carton is one- but individually wrapping them and laying them in a single layer is the way I do it. I line a box with bubble wrap, put cardboard partitions in to keep any eggs knocking each other. I wrap each egg in soft paper and top them with more bubble wrap. wrap the box in more bubble wrap and put it into a bigger shipping box and pack all space with bubble wrap. I have only ever lost one egg in transit sending them in the post like that.
A few tips to help with shipping fertile eggs. Make sure your fertility is high by test incubating when offering fertile eggs for sale. Dont send eggs durring extremes in temperature. The middle of summer and winter are not good times for shipping eggs. Cushioning the eggs so they have shock absobancy in the packing can help to iliminate detached aircells.
I shipped a dozen last year via USPS Priority Mail. I used an egg carton, put in some clean hay (not straw-too bulky) and secured the lid with tape.
Then I packed the shipping box with packing peanuts an crumpled newspaper. On the outside of the box label clearly that there are perishable duck eggs and FRAGILE. I put insurance on the package as well. Worked.