From Bugzilla Helper:

Description of problem:
mailman has the ability to auto-process bounce messages and then remove people 
from a mailing list or just stop attempting to deliver mail until mail deliver 
is reenabled.  Setting users to "no deliver" doesn't seem to work, but removing 
users does work.

How reproducible:
Always

Steps to Reproduce:
1. Set up a list.
2. Add a non-existant mail address to the list.
3. In the "Bounce Options" section of the admin page, set "Action when critical 
or excessive bounces are detected" to "Disable and notify me".
4. Send enough messages to the list so that it is considered excessive.  Watch 
the mailman logs to see when an excessive number has been reached.
	
Actual Results:  Nothing.  The fact that there had been an excessive number of 
failures was recorded in the logs, but the user was not shown as disabled on 
the "List members" page.  Also mailman continued to try to send mail to this 
person.

Expected Results:  Mailman should disable delivery of mail to this problem user 
and notify the list administrator.

Additional info:

I also tried setting the bounce action to "remove and notify me" and that *did* 
work.