When you can not use your browser for email.

Every mailing list really has two addresses: the list name, where posts should be sent, and the list name followed by -request, where commands to the listserver software should be sent. For example, posts to ROOTS-L should go to ROOTS-L@rootsweb.com while "subscribe" and "unsubscribe" requests should go to ROOTS-L-request@rootsweb.com.