Where's the Mailbox?

Where&#39;s the Mailbox? is a collections achievement awarded for acquiring a single heirloom in the heirlooms tab, the first in a series.

Series

 * 1) Where's the Mailbox?
 * 2) Alt-ernative Lifestyle
 * 3) Ready for Powerleveling
 * 4) Heirloom Hoarder