The List Description is a short sentence describing the purpose of your mailing list. It needs to fit on one line, and be less than 80 characters in length.
You can find this setting under "List Moderator Settings" in your mail-list account after you click on "Customize Your List".
Type in your list description in the box under "List Description":
Make sure that you save your settings.
In order to get the detailed step-by-step instructions on how to save the settings, please refer to this link: