3 Mailman's interfaces

Mailman has two different interfaces for the list subscriber: the web interface and the email interface. Most discussion list subscribers use the email interface, since this includes the email address you use to send mail to all the subscribers of that list.

The interface you use for changing options is largely a matter of preference, since most (but not all) of the options which can be changed from the web interface can also be changed by email. Usually it is easier to use the web interface for changing options, since the web interface provides instructions as you go, but there are times when people may prefer the email interface, so both are provided.