What concerns me the most about this topic is not the poorly written email or message board per se, but more so the lack of the ability to perceive the difference between social situations.

If I send a text to my best friend that says, "C U in 5", that's alright. She knows I mean "See you in five minutes", and it is very informal.

However, I am not only capable of conversing in proper English, but I know when it is only appropriate to do so. I have a firm grasp of the informality vs. formality of various situations.

I honestly don't think a lot of people do, and that's rather frightening.

I have friends who are teachers who say high school students turn in paper in English class with LOL speak freely interspersed, and can't understand why they lost points. Seriously? Sadly, yes.