I have the mailman extension set up and it accomplishes subscriptions to the list, but it does not trigger the sending of a welcome message to the new subscriber. I really need this, because there are some instructions about how to use the list, etc. Is this a known problem or is it something with my configuration?

BTW, I do not add lists directly from Mailman, but through a Plesk admin panel (version 9.2). My Mailman is version 2.1.9.

Update: August 10, 2009

One of my lists is configured as "Approve and Confirm" and this is also completely ignored when users click the subscribe button. I suppose this might be unnecessary, since there are approved groups and the user must be logged in, but it might be a clue as to the welcome message problem. It appears the entire config is being ignored.