I've recently found myself typing "Sent from my wireless device" at the end of an email sent from my desktop. It's shorthand for "You know this is just email, right?"
Some people react to perceived tone in email, a medium in which we compose in a hurry, usually while distracted. Emails that are written for the optimal distribution of information can seem terse, almost dismissive; and can provoke emotional reactions that get in the way of actual work.
We all need to remind one another that emails are not letters. The best email writers are careful and reread before hitting 'send' – but if you're spending hours composing emails, with sensitivity for tone instead of clarity, selecting synonyms to avoid every possibility of slight, then you're probably doing it wrong. Instead, try this: include some cues that, hey, this is email: don't read too much into it. The occasionally spelling or grammatical error, provided that it does not obscure meaning, serves the same function.
Posted from my wireless device.