Ruthie,
it seems n IO, that once i invite someone, as long as they reply, even
with a blank email, they automatically get added to the group.
Correct. Just as in Yahoo Groups, an invitation constitutes approval of the member.
is there a way to keep an invited person in the pending status, until
we approve their membership?
Don't invite them. Instead send them an email with a mailto: link for the +subscribe command, and/or an http: link to the group's home page.
Shal
Shal Farley