> Bad Grammar is a courtesy.

I agree. Or at least to the extent that the complaint is that bad grammar signifies dispensing with formality, dispensing with formality is often a courtesy.

Too many people have it drilled into them that "If a job is worth doing, it is worth doing well" when in reality if a job is worth doing, it is often worth doing very badly indeed, because it really, really just needs to be done.

It takes a large amount of very unproductive navel-gazing to assume that a message that unequivocally gives you the information you need, yet that doesn't measure up to your own perceptions of how much effort should have gone into the crafting of the email, is an insult directed at you, rather than a focus on the message rather than the medium.

Even if Marshall McLuhan's dictum is correctly applied to this scenario, the message conveyed by the medium could well be "Stop wasting so much time agonizing over phrasing! Just spit it out!" rather than "I'm better than you so I can get away with sloppy shit that I would excoriate you for."