e-newsletter won't send: get error message: "invalid email address you must provide at lea

What on earth?

This plugin needs some documentation.

In the mean time, can anyone explain to me what I need to do to get this thing to work? I've been able to successfully send test emails many times, as well as sending to site admins.

However, when I go to send to all members of a group, I get this error:

"Invalid: email addressYou must provide at least one recipient email address"