Can I sue a former colleague for libel for sending an email containing false accusations naming me to our colleagues?

He resigned of his own volition. After leaving, he sent an email containing false accusations and naming me many times to nearly 100 of our colleagues. He says that I'm the reason he left and encouraged them to "make things right." We did not work directly together very often, but he never said anything to me or our supervisor about these complaints, so we are stunned. I'm angry, but I want to handle this correctly. He had worked here a long time and many people who know him better than they know me will think very badly of me now. This could affect my future prospects with the company and my relationships with my colleagues. Do I have legal recourse?