Matt - I took the liberty of moving this to the Shipping Forum.
To clarify just a few things:
Choice of carrier- You mentioned USPS, and specified that you will be shipping cornsnakes...push that idea out of your head right now. It is against the law to ship snakes via USPS (some reptiles are allowed - the specifics are posted within this forum, and should be easily found with the search function). Currently, the only overnight carrier that accepts snakes specifically is FedEx, and they require the shipper to obtain a special waiver (there are plenty of posts/threads in this forum regarding that process). UPS' and DHL's TOS specifically state that they do not ship snakes (again, some reptiles are acceptable; and, again, the specifics have been posted here multiple times.) You will probably note that there has been much debate on that subject; the reason is simple: many of the large breeders/dealers use UPS exclusively, apparently with their blessing, while most of us are flat out refused service because we are shipping snakes. DHL plays a similar game, with some reps welcoming reptile shippers...the problem arises when one actually attempts to ship, and the package is refused In several cases, Fauna members have been told to mislabel the package contents by their reps, in order to get the packages accepted (again, their TOS prohibits snakes). It should be noted that the TOS of the overnight carriers all allow them to halt the delivery of any package in violation of their TOS, which means that just because a package is accepted at your local facility, does not mean it will make it to the destination...if they learn, or suspect, that a box contains snakes, they are within their rights to stop its progress at any point along the line (I'm pretty sure that I have read a couple of accounts where that has happened to people, too).
Another option is to utilize the airlines. Delta Dash is probably the most commonly used service, and it offers same day service and guaranteed flight times. D-Dash does require a shipper to undergo a simple process to become "recognized". There is also Delta Cargo (Freight), this used to be the "normal" method of shipping reptiles, but there is no guaranteed arrival time...and freight is not the highest priority (meaning that packages would get
bumped to later flights...my worst experience with that was a box of snakes being delayed 3 days in mid winter).
I have not utilized their service, but Northwest Airlines will also accept reptiles (including snakes) for same day delivery - and they do not require any special waiver/permit/paperwork. I have spoken at some length with a NWA shipping representative - she was very helpful and made the service sound very accommodating. The cost seemed to be quite comparable to Delta Dash.
Labeling It is required that anyone shipping live animals label the package with the contents. This includes listing both the common and scientific names (genus + species + subspecies, if applicable), as well as the quantity of each. Failing to do so, or intentionally mislabeling, is a violation of the Lacey Act (a Federal Law) and can carry stiff penalties if one is caught.
Packaging Preparing a package for shipment is easy, but it is surprising how many people do a poor job of it. Chris, from TSE, posted a great
How To thread....regardless of what he turned out to be, that
was a great post. You should be able to locate it by searching "how to ship" in this forum. Clay Davenport also has an excellent instructional on his site...you can find it at:
http://arbreptiles.com/shipping/index.shtml (for the record, I only mentioned Chris' thread first because it can be found on this site, within this forum)