Katy's Stampwhistle
Drops from Bulging Package. (Nearly) Everything you could have possibly come here to learn about: This toy is account-bound.
Katy's Stampwhistle is a Legion toy that summons a functional mailbox NPC named Katy, obtained by completing the Postmaster quest chain in Dalaran.
Guide awaiting review
Find the Lost Mail
Search near a mailbox in Dalaran for the 
Lost Mail on the ground. It respawns approximately every 2 hours and is bind-on-equip, so it can also be traded to a friend.
Deliver to Madam Goya
Bring the Lost Mail to Madam Goya in the Underbelly of Dalaran to begin the quest chain.
Report to the Dalaran Mailroom
After turning in the Lost Mail, you will receive a mail from the Postmaster directing you to the Dalaran Mailroom, which is accessible near the pet cemetery.
Sort the Flying Mail
Inside the Mailroom, sort 9 pieces of flying mail to progress the quest chain.
Deliver the Solid Stone
Complete the A Huge Package step by delivering 1,362 
Solid Stone, a throwback to The Bank of Vernal in Utah, USA.
Return Invincible's Reins
In the Priority Delivery step, retrieve and return the 
Invincible's Reins to their rightful owner, which involves combat.
Complete the Delivery Locations
Deliver mail to named locations across Kalimdor, Eastern Kingdoms, Outland, Northrend, and Pandaria — including towns such as Astranaar, Kharanos, Sylvanaar, Camp Oneqwah, and Longying Outpost — to earn the Postmaster title and unlock the 
Katy's Stampwhistle toy.
Tips
Katy's Stampwhistle is account-bound, so unlocking it on one character makes it available to all your characters regardless of faction.
Each character gets its own independent 3-hour cooldown on the stampwhistle, and it does not share a cooldown with the Engineer's
MOLL-E.Other players of your faction can interact with Katy and even send or receive mail through her, but opposite-faction players cannot.
Katy works inside instances but will disappear if the summoning character moves too far away or leaves the zone.
This toy cannot be used in the Pandaren Starting Zone, but it does work in the Demon Hunter starting zone.
See the video guides for a full walkthrough of the quest chain steps.
