If you use S/MIME to sign or encrypt email messages, you should not delete your personal certificate, even after it expires. Doing so would cause you to permanently lose access to those messages.
However, most users at MIT do not use S/MIME, and can safely delete their old or expired certificates.
If you are not sure, you may want to:
- [Check whether you are using S/MIME for email signing/encryption] (in archive, login to access)
- Export or Back Up Your MIT Personal Certificates