You just need to go to Blasted lands city Nethegarde keep or smth :)

If you're at max exalted with Stormwind, don't bother. It gives no overflow alliance rep as most quests do. I picked this up every time I went through the swamp while doing loremaster, and I tested the last time at 999/1000 exalted, and received no rep at all with any alliance faction. As stated above, it doesn't count for loremaster, not that you should be hurting for quests in the eastern kingdoms as alliance anyway.

If you're grinding rep - although this is a useful bonus if you're going to be making the trip anyway - I would recommend doing other quests first instead of going out of your way to pick this up for rep. Even as an older Night Elf character that did many of the alliance quests back when reputation gains experienced diminishing returns if the quest was green, I was still at exalted with Stormwind before I went back to do the Human 1-20 area quests.

Waste of time XP wise, got 25 rep with Stormwind and the crate contained 3 silver and a Scroll of Intellect. Jackpot.

This quest should be classed as repeatable in my opinion.