We reported earier this week that Blizzard will start cracking down on the use of third-party input broadcasting software, also known as the chosen tool of the multiboxer. And the great purge has begun in earnest, with users of such software receiving the warning below.
Blizzard started sending out those warnings to a lot of people yesterday, in both Retail and Classic. from r/wow
After its initial announcement earlier this week, Blizzard did clarify that multi-boxing itself wasn't against the terms of service, but using third party software to do so was. That is an extremely fine distinction because, while it's possible to multibox in a fashion without third-party software, you can't really do so efficiently: and multiboxing is all about efficiency.
Farewell, then, to the synchronised swimmers and hivemind herb-gatherers of Azeroth. And don't let the door hit your third-party software on the way out.