> What I need is a list which is sent to as (example) [log in to unmask] and sends
> out from [log in to unmask]

Look for the section about the List-Address header field in the file
LISTOWNR MEMO distributed with LISTSERV.  This will probably give you
the right hints.  Further, you'll probably want to set aliases for
LISTSERV and all list names on the remote domain's MX host or direct
the mail completely to your server by adding a MX record pointing to
your LISTSERV host in the remote domain's zone file.

> without users seeing that the listserv and
> LSMTP servers are beeb.com hosted.

AFAIK it's absolutely impossible by concept to have the LISTSERV
address different for each list, which is for example used in command
job requests (SUBSCRIBE, SIGNOFF, etc., all the commands).  Further,
LSMTP and LISTSERV will leave some traces in the Received headers of
each mail, which can't be avoided, too.

-- Peter 'Rattacresh' Backes, [log in to unmask]
   TURN OFF AUTO-QUOTING OF THE WHOLE TEXT IF YOU REPLY!!!