World of Warcraft immigration rules are up to date.

If you exceed the limit, you can't hand it in, and you can't completely keep the excess, let alone automatically transfer it to other trumpet. If you must transfer money, you can manually transfer the gold coins to another number, or use the extra G to buy a batch of goods and sell them after the transfer. The goods are not limited, so this method is feasible, but be careful not to misread the market and smash the goods in your own hands.