The full text of Justin Barrett's email is here.
There are some lessons here:
Always get someone you trust to proofread your screeds.
When you are the trusted friend, be sure to ask him, "What is the purpose of your writing? What outcome are you trying to achieve? How does what you actually wrote advance that goal?"
If the answer to the first question is, "Venting my spleen," then tell the writer that maybe he should find a more constructive goal.
Of course, always be careful about using the office email system.