I don't know about you, but I hate the mailbox dance. I try my best to maximize my playing time and minimizing my bank alt time while being as efficient as possible.
After discovering this trick Stormwind became my Auction House of choice. This should work in Undercity as well since the auctioneer / mailbox are close enough.
I do realize that this won't be incredibly useful to a large portion of the community, but hopefully a few people benefit as I've quite a bit of time in to it.
I didn't find any other posts on this topic at all via the search tool, I'm pretty sure this isn't a repost.
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This macro allows you to stand by the SW mailbox outside of the AH and use the AH at the same time. Absolutely no movement at all! You just need to go to your spell bindings and bind interact target to a button.
So what you do is first of all, make this macro:
/cleartarget
/targetexact Auctioneer Jaxon
/cleartarget [dead] [noexists]
Next, go into your Key Bindings setup and set a key for 'Interact with Target'. It's under the Targeting Functions section.
Then you'll want to stand right here in Stormwind:
Use the macro, hit your key bind and voila! AH and Mailbox without moving a step!
Now Hordies, stop raiding SW every 2 hours so I can use this little trick.