It is illegal to ship "yeast samples" by the US mail. Felony illegal.
Ship via UPS or FedEx, where it is not illegal but against company policy, but tell them you're shipping sauces and marinades. If you picture Paxton in your head while writing it on the form, you are not technically lying.
Wrap each bottle in bubble wrap and pack well with newspaper or other packing material. (I put a couple of sections of the local paper on the bottom of the box, and then insert a black trash bag, then another layer of newspaper in case of breakage.)
Maybe one day AHA will get UPS and FedEx to change their policy. . .