Sending cremated remains in the mail
If you are sending cremated remains within the United States, they must be sent as either registered mail or express mail. If you are sending cremated remains internationally, the remains must be sent as registered mail and the customs form must clearly state that the package contains human remains. Some countries may have restrictions on receiving packages containing human remains, so it’s best to check the mail requirements of the country receiving the package before sending it.
Traveling with cremated remains
There are no rules on traveling with cremated remains. If you are bringing cremated remains on an airplane, you can either carry them on the plane as carry-on or check the remains in your luggage. The remains will be screened using an x-ray machine, so be sure that they are packaged in a material that the scanner can see through, such as cardboard, plastic, or wood (rather than metal or stone).
If you'll be carrying the remains on as carry-on, be sure to tell the security agents that you're traveling with cremated remains so that they'll handle the remains properly. It might also be a good idea to have any paperwork related to the cremation with you, to show to TSA agents so that there's no confusion. As all airlines have different rules, it's a good idea to check with your airline for details and specific regulations around traveling with cremated remains.