I'm not sure if drop trading is possible anymore, but DON'T RISK IT! It is much simpler to just open 2 windows simultaneously and trade that way.
All you have to do is load the game up twice, either in 2 seperate browsers, or in my case I use the desktop client and an internet browser. Get both accounts that you want to trade with into the lobby and qued up to log into the exact same world. Shrink the windows so that they are side-by-side and then as soon as you press "log in" on one window, immediately press it in the next before the first character loads into the game. If you do it fast enough and click the buttons a second apart, it should load both characters into the game on the same world. Then just meet up and trade to your hearts content
This is what I do to transfer gold/items between ALL of my characters.
Yes, you can drop trade, I saw someone get scammed out of 20m a few days ago, however this was in the Wilderness so I don't know if it applies to non wildy.