The US postal service has specific guidelines on shipping poultry. You can ship them as DAY olds, because they can live off the yolk for up to 72 hours but after that, no. You can also ship adults, after they have reached a certain age (not sure what that age is). You have to provide food/fluids in the form of fruit in the box for their journey and use boxes designed for shipping poulty.
The USPS also has guidelines on when they will ship, depending on the weather. Again, not sure of the specifics, but it can't be too hot or too cold along their route.