Gold exchange Icecrown Outland

Greetings!
I'd like to ask is it allowed if i put on messages on either one of the realms and ask for a gold exchange, example: Looking for someone to trade Gold i give 1k on icecrown u give me 100 gold on Outland.Is it allowed to do this cause i don't wanna get banned please anwser.
With Kind Regards, Warmane Player.

There is a legit, scam-free way to do this, no?

Sell gold on icecrown for coins
-> buy gold for coins on outland

Please someone else anwser, need to know for sure.