Often, it's easier to simply give an example than explain exactly how to find the address for your specific list. As such, we'll frequently give examples for a fictional list called LISTNAME@DOMAIN whose list information page can be found at http://WEBSERVER/mailman/listinfo/LISTNAME.
Neither of these are real addresses, but they show the form of a typical list address. The capital letters used for the list-specific parts of each address should make it easier to see what should be changed for each list. Although specific list configurations may be different, you will probably be able to just replace the words given in capital letters with the appropriate values for a real list:
As a real-life example, if you are interested in the mailman-users list, you'd make the following substitutions: LISTNAME=mailman-users, DOMAIN=python.org, WEBSERVER=mail.python.org. As such, for the firstname.lastname@example.org mailing list, the list information page can be found at the URL http://mail.python.org/mailman/listinfo/mailman-users. (These, unlike most of the examples given in this document, are real addresses.)
Most lists will have this information stored in the List-*: headers. Many mail programs will hide these by default, so you may have to choose to view full headers before you can see these informational headers.