Heya!
So with this new 4.3 addition "Transmogrify" you can change the appearance of armor, even Hierlooms.
BUT! Blizzard said that "If you trade, mail or put items into bank, the transmogrify will get removed"
But here's how to bypass it:
1. Log your main with awesome gear
2. EQUIP the Hierlooms and transmogrify to the awesome gear
3. Open mailbox and open the gear tab (C)
4. DRAG from the gear tab to mailbox and mail the items one by one.
5. ???
6. Profit
The key here is nr. 4! If you for example put the hierlooms into bag FIRST, THEN mail it, it will fail. You have to drag it directly from gear tab to mailbox!
PROOF: http://i44.tinypic.com/357m5hk.jpg