The game's collection data lists Sul'lithuz Sandmail as sold by a vendor NPC in Warspear.
Vendor
Zone
Map
Waypoint
Other items it sells
NPC #93917
Warspear
-
-
169
Vendor NPC, zone and position come from the client's collection source tables (CollectableSourceInfo and CollectableSourceVendorSparse); coordinates are the in-game map readout.
Build history
First seen in build 5.5.4.69585 (Mists of Pandaria).
Read from the World of Warcraft client build files.
How Sul'lithuz Sandmail Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Sul'lithuz Sandmail suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Transmog Sets
Sul'lithuz Sandmail is part of the transmog set Regalia of the Witch Doctor (Shaman only). The other 16 pieces:
4 other items in the current build are also called Sul'lithuz Sandmail. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Blizzard numbers items as they are created, so the named items next to ID 96021 (96016 to 96026) were usually added in the same batch as Sul'lithuz Sandmail: the same quest line, zone, vendor or reward set.