Silverwing Emissaries are level 22 Warsong Gulch recruiters located at various spots throughout the largest Alliance cities - Darnassus, Ironforge, and Stormwind.
NOTE: They are only available during the monthly (Call to Arms: Warsong Gulch).
See List of Darnassus NPCs, List of Ironforge NPCs, and List of Stormwind NPCs.