Subscribing to a mailing list using your Web Login information
From the Mailman home page, select Browse Advertised Lists. A list of all the publically-advertised lists appears.
Click on the list you wish to subscribe to. The list's information page appears.
Under the "Subscribing to [list name]" section, click Log in via login.cmu.edu (on the right side of the screen). You will be logged in through the Web Login service, then brought back to the list's information page.
A new button will have appeared in place of the "Log in via login.cmu.edu" button; it is labeled Subscribe as [your email address]. Click this button to subscribe to the list.