did a few searches and couldn't find this one anywhere so sorry if it's a repost.
There is a spot right outside the Sw auction house where you can access both the ah and the mailbox. I use this so I can repost my glyphs faster after canceling them. (fierce Glyph competition on my server)
http://a.imageshack.us/img36/7950/mailauction.jpg
To use the auctioneer simply walk into the corner shown in the picture, turn on name plates, and move your camera back towards the door. Right click on the name plate without targeting then auctioneer, and go on your way reposting auctions faster than your competition.