The Mailman program requires you to choose a password when you subscribe to a list. You use this password later when you want to change your list settings or unsubscribe. Make a note of the password when you choose it. You may want to use the same password for all your UUA lists, but do not use a valuable password (like the one you use when you connect to the Internet or retrieve your email), as it will occasionally be emailed back to you in unencoded text.
If you've forgotten your password, go to http://lists.uua.org/mailman/options/listname/emailaddress (replace "listname" with the name of the list and "emailaddress" with the email address subscribed to the list) and hit the "Remind" button. You can also email the one-word command "password" (in the subject line or message body of an email message) to email@example.com.
Most lists send a reminder once a month of what lists you're subscribed to and what your password is. You may change this setting on your list options page (http://lists.uua.org/mailman/options/listname/emailaddress) by selecting "No" in response to the "Get password reminder email for this list?" question, then clicking the "Submit My Changes" button at the bottom of the page.