Oh, one more thing:
when I use the bulk add feature, to add many people to a mailing list,
usually several people are not added, because their email address is
already in another mailing list.
I usually want these people to be added to the (new) list anyway, even
if they're already in another list. Maybe you could add a checkbox for
"add emails even if already in another mailing list". Of course, if
they are already in the (new) mailing list, they should not be added
again.
Oliver