The security certificate used for SSL/encrypted communication between e-mail clients and the imap.science.oregonstate.edu server expired on Saturday without warning/notification. We are working to renew this ASAP. Until then, you can safely ignore any messages which your e-mail client might show you regarding an expired certificate.
UPDATE: The new certificate was installed today at 8:30am. If you encounter any further problems connecting to the e-mail server via SSL, please contact the helpdesk.