It depends on how it's done. If it's part of the real message then it's easily ignored and no harm done, if it's a separate message then it wastes the time of w

It depends on how it's done. If it's part of the real message then it's easily ignored and no harm done, if it's a separate message then it wastes the time of whoever is on the receiving end (especially if they wait for a response before sending the real message).