If you are getting "You must supply a valid email address" when you attempt to subscribe, Mailman probably has the wrong url for it's website and is being redirected back to the real one which loses POST form data. This is annoying to fix as the config option isn't available through the website. However it can be fixed by using the withlist script.
bin/withlist listname m.Lock() m.web_page_url="url" m.Save() ^D
No page links to MailManNotes.
