[Mailman-Users] Unsubscribe/Send password not working

[Eric Elder]

My mailman's working fine, people can subscribe and they get the 
confirmation message, and users can post messages to the list.

But when they try to unsubscribe or get their password sent to them 
using the web interface, they never get a confirmation message sent to 
them.

Where would I look to try to find out why this is happening?

(P.S. I have another list on the same server that uses a different 
domain name for the web interface, and the unsubscribe feature works 
fine on that domain.  It's just on this 2nd domain that it is failing, 
if that gives any more clues.)

Thanks,
Eric