Step 1: Login to https://lists.gatech.edu using your GT credentials.
Step 2: Click on "Your preferences" located at the center of the band at the top of the page.
Step 3: In the "Changing your email address" section, enter your new email address.
Step 4: Confirm the request by clicking on the "confirm this change request" link in the new email address' account.
NOTE: Some lists require list owner approval for updates so it may take extra time to get changed.