Not the seedlings but the cutting from a mature plant [pruning's] are the best. I would leave a couple leaves at the top so they know what end to put in soil. I received mine in hot weather they were all sweaty and I did not expect them to live. They were just very small cuttings which do not do so well most of the time but I ended up with 4 out of 6 that are now doing just fine. So at least for me if you want to send them in the mail I would just do branch cuttings-prunings. If you are just hauling them why not just keep a ball of dirt around them placing them in plastic bags? As long as they are dormant they do not need much moisture. Also you did not say for what reason you needed for them to be dormant, etc.