Earlier quoted context omitted.
It was the day before. Your point about it being an email is exactly my point this could be taken as him knowing something that nobody else did and thus selling his shares. Just looks odd
In this the "something else" would be knowing that the CEO is about to send a stupid email the next day? If he anticipated it would leak and tank the stock wouldn't he have more likely just run it by some folks and sent something less poorly worded?
Another user in this thread pointed out that this seems to be a monthly thing the CEO does, so this no longer appears as strange.