Can
e-mail recipients be listed in multiple categories?
Yes,
but the e-mail address must be added to each category as a
separate address.
Can
users opt-out of broadcast mail list?
Yes. Users
must opt-in to the mailing lists after they sign-up. And,
each message that is sent out includes a link at the bottom
of the message that recipients can click on to opt-out of
the list.