That error doesn't actually have anything to do with "spamming" in the normal sense.

Error 318
You have been dropped from the server because you reached the message rate limit. Please avoid excessive messaging (i.e spamming).

What it means is your client reached the message rate limit with the server, it usually occurs when you lag a little, maybe even for a few seconds, and you keep hammering the "A" button to interact with something or trying to cast an ability. When your connection catches up you flood the server with "Do <x>" messages and it boots you for exceeding the limit.

It's a badly worded error message, that's for sure.