[Mailman-Users] Any way to disable passwords?

[Jordan Graham]

I'm a new user of Mailman, and have a long list of email addresses from
which inquiries have come to me, many of which are no longer valid.  Is
there a way to:

1.  Disable passwords, so that by simply replying to an email from the list
with the word "unsubscribe" in the subject line, a user can be removed?

2.  Have fatal "undeliverable" notices automatically remove that user from
the list?

Thanks in advance for your help.

Jordan Graham