Ok so i haven't seen this anywhere on this forum and i check it 3 times a week since the release of MoP so here goes.
If you're a botter like myself and CoD some excess herbs/ore then you may accidentally come across this.
If you CoD items to someone and they pay for it but don't take it out of the mail then it gets sent back to you after 2 days. So you got the gold and items back 3 days later.
If you didnt get that heres what happened to me
1; CoD'd someone about 40k of Ghost Iron Ore and told them i needed them to pay fast because i wanted to buy a mount tonight for my grilfriend. (Shitty excuse lol)
2; I got the gold 2 hours later.
3; They didnt take the ore out of the mailbox. (40k of ghost iron ore is heavy on the bags.)
4; 2 days later the CoD return system sent the ores back to me.
5; I know have the gold and 34k's worth of Ghost Iron Ore.
Obviously its luck whether they take the bait and pay then leave the stuff in the mail.
One way to increase chances would be to CoD alot of things at a time, like i did.
YOU CAN'T GET BANNED FOR THIS AS IT ISN'T YOUR FAULT.
Hope this helps someone.
-Dosh