Underlib, the Libraries' informal email list, is a Mailman list. Past posts are archived and searchable, although not easily. Through the web interface, you can subscribe, unsubscribe, view a list of members or search the archives. You can change your password.
Didn't know you had a password to underlib? If you are a member and didn't choose a password, a random password was assigned you.
You can get a password reminder (needed to change it) by clicking on Unsubscribe or edit options in the Underlib Subscribers section at the bottom of the mailman webpage.
Go to the web interface at http://mailman.mit.edu/mailman/listinfo/underlib