Can Alliance mail heirlooms to Horde?

Hello all, I was just wondering if I could mail heirlooms from an Alliance to one of my horde toons. Haven't tried it yet because I'm worried I would send it to some weird person I don't know. Let's say that I have a Horde main, then I buy an heirloom and send it to my Alliance alts. Will it get there, or will it fail?

Just curious, and would love a good answer. Thanks