My home is in Hawaii, where we have an absurd abundance of these magical Rainbow Trees that I have been sustainably harvesting some ACRB . The meat of the bark is nice and blood red, which I was told the more redder, more better. My question is: What is the best way to dry the bark and send to be mainland without it arriving moldy? Is it best to dry it indoors away from the sun or outdoors in the sun? Please pardon me as this is my first post on this forum. Aloha!!

im thinking that you should cut it as small as you can for better and equled drying, and put it on a screen to dry in low humid area, you probbebly can dry it in the sun cause its bark, if it was flowers of more gental part of the plant the shade would be better.
maybe after you think its dry you can put it in food dehydrator for extra drying and to make sure that theres the least amount of moister that can be.
btw are you cutting only the root cortex(bark)? the whole root will be just waste of time

Aloha! And welcome, it's nice to see so many Islanders joining the Nexus. Definitely keep the bark out of the sun. Just cut it up into strips or squares and put it on some kind of screen inside with a fan blowing on it for a few days. I was born and raised on Oahu so I know how wet it can be, if it won't dry indoors then you can stick it in the oven on low with the door cracked open a bit. That would dry it pretty quick without much damage. I've also had good luck with drying small amounts of shredded bark that way. Though if I'm extracting I never dry it, fresh bark works way better. If you can, try not to leave exposed parts of the inner tree it can eventually rot and kill the whole tree. I've found it's best to find an exposed root and just cut one or two off each tree and let it heal for six months to a year before coming back to it.