Mail list issue

[Mainship]

I took a look at the mail list capability that Plesk offers, and I find it lacking. I have a client that wants a list that allows her to approve/disapprove subscribers and to moderate all posts. Pleak's list doesn't seem to have any moderator capabilities, other than to add or delete subscribers from the control panel.

Is there something I'm missing? If not, is there something else you would recommend I use? I'm not anticipating any real volume if that makes a difference. I also want to keep the cost down.