The main thing I'm considering...is how hot it will be in the mail truck. There is little to no air movement in the back of the vehicle...so the temperature will be higher than the front of the truck where there is air movement.
Hi! I'll have to check my records and contact the folks that got the eggs --- but I shipped eggs last year right through our 100+ degree heat wave.
I had a pen go 'infertile' from the heat --- but it wasn't a postal / shipping issue.
If your shipper:
-collects eggs often and stores cool til ready to wrap and pack.
-packs well with insulating bubblewrap,
-marks the box as 'perishable', 'protect from heat', etc.