Can`t Mail

So people told me you CAN mail Heirlooms from alliance to horde and vice versa, but when i ty to mail a Venerable Mass of McGovan from my troll shaman to a worgen rogue, it just says internal mail database error, and doesnt send anything. I have no idea what could be causing this error or how to fix it.

ok, i actually figured it out, i couldnt send it because it was imbued with the shaman spell, for anyone having the probelm, equip the weapon and right click the imbue buff.