Edit: SOME of the heat issues have been solved, and leaks are now non-existent. Given your package DOES NOT sit out in the sun for more than 4 hours, it will arrive unscathed and just as potent as it was when I put it into the mailbox. If however your package is exposed to high temperatures (above 100 degrees Fahrenheit) it will cause the vacuum sealed package to inflate like a balloon, if it inflates too much it may pop and/or the liquid may leak and potency is lost very quickly at this point. SO KEEP IT OUT OF THE SUN AND HEAT.
I managed to do some rather extensive testing last week, with a combination of electrical tape, baking soda, and vacuum sealing, I have managed to make the product survive a minimum of 4 hours in direct sunlight on the hood of a car. The bag puffed out nearly to the point where it might pop, but no liquid leaked out at all! There was a very slight dampness under some of the electrical tape from condensation I believe because there was no smell to it. But I marked the fluid level with a paint marker and it did not go down at all! Also the popper seemed significantly stronger than it was before the heat test, no scientific measurements were taken so this really could have just been due to my excitement that it didn’t leak at all. I’m not even sure how one could go about measuring the effects strength in a scientific way… I guess one could record the length of time effects last but other than that I don’t know.
Interesting fact: the strength of hallucinogenic compounds given to lab rats used to be ranked by how many violent head twitches per minute the mice expressed after getting dosed up. (source)