> 1) Why does a user get blacklisted.
When a user unsubscribes, he is blacklisted. Which means that no mails, not
even system mails, are sent to him.
> 2) What about the users who have not confirmed. Is there a way to
> resend a request for confirmation mail to them.
Yes, there is such a feature.
Manage Users -> Reconcile Users has many useful links - scroll till the bottom
of the page to see all of them.
> 3) I have sent a mail to AOL users and asked them to subscribe from a
> different domain and deleted them from the list. Are there any other
> domains which give a similar problem?
You can check using "view bounces". Read the reason given by the mailer daemon
for the bounce.
> 4)Is there anything else which I need to know or manage?
Very good documentation at http://docs.phplist.com/Documentation