It's been a while, but I'm back. At a local company today, an email went out advertising benefits to all the part-time employees who worked there, linked to a phone number for the HR department. Upon further examination, no one knew who sent the email. HR hadn't approved it. If a prank, it was deliberate and malicious. If an accident, it was truly unfortunate. The poor receptionist at the front desk was swamped with dozens of curious employees all asking the same question, and she didn't have any more information than the rest of them.
Ideas spread like wildfire—all it takes is a one sentence email to get people acting. It just takes the right sentence. People who take action about something they care about.
So figure out what people care about. And write the sentence.