If I write it in an email and then describe it in the calendar invitation, put it on the website and also announce it at the meeting, and people still don’t get it, I haven’t done my work.
We haven’t communicated when we have fed the input into the machine. We’ve communicated when we’ve been heard and understood. Ignored maybe, but heard.
It’s tempting to blame the receivers for not paying close enough attention or for being distracted. But we knew that about them before we sent the message.
YoRocko! 
Gotcha! I have heard that this is the origin of the military’s “aye-aye, sir.” One “aye” is “message received” and one is “message understood.”