This is where you can change your "receiving mode" options for your lists and whether or not you wish to reveal your email address.
If you have not already done so, log into the web interface.
On the left hand side of the screen, you will see a list of the lists you are subscribed to. Click on one of them, then click on "Subscriber Options".
If you click on the "up and down pointers/arrows" beside "standard (direct reception)" you will get a list of "Receiving modes". If you want an explanation of what each mode does, then click on the "Help" button.
If you do not wish your email address to be viewed by other people, select "concealed".
Once you have finished selecting your subscriber options, click on "Update" to commit your changes.