Removing all doubt...
If you drop a letter in the post office mail slot and instantly realize you were mistaken to send it off just yet, you can go to the ladies at the counter and beg mercy and they'll usually dig your letter out. However, when you press "send" on an email, there's no snatching it back from the ether in that dread instant your eye zeroes in on the humiliating grammatical error it refused to see mere moments earlier.
Really. I'm not illiterate. Mostly.