For some, e-mail is perfect for writing a couple of short paragraphs. They might not be well-constructed. The punctuation, grammar and spelling might be sloppy. But for some, e-mail is a sign of character. I am concerned that it's taken the right way.
People make quick judgments about other people based on little information.
If they see sloppy e-mail, they're going to make attributions about competency or intelligence or conscientiousness. Just in the same way that your business letters are judged for those things, your e-mail may be judged. If you find it difficult to communicate gracefully regardless of the medium, use e-mail to distribute facts rather than opinions. Let the wordsmiths duke out the sensitive stuff with e-mail. Even if you try to be sensitive, inevitably, someone's going to misunderstand you at some point.