The MIT Alumni Network Services has developed a service entitled "E-mail Forwarding for Life" that gives alumni a permanent mail address from MIT. This service is free and easy to register for; just go to https://alumsso.mit.edu/cas/login?service=https%3A//alum.mit.edu/casservice to fill out the registration form. You must have an Infinite Connection account to use the service.
Please note that this is not a permanent Athena account; rather, it is a way to forward mail to your account at your work or other service provider. It will, however, give you a permanent address at MIT that people can send to, given that you have another account configured to receive the forwarded mail.