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.
For more information, please contact the Alumni Association at http://alum.mit.edu/contact/