Email server control panel

[Mad Unix]

I have installed QMAIL , Vpopmail , courier-imap , Qmailadmin ,
Vqadmin, MySql , Spamassassin , clamav and Squirrelmail
under Redhat 9 / RHEL3 / FreeBSD 4.x 5.x each machine serve over 300 users.


>        I was hoping somebody here might have a solution for my problem.  I
> am wanting to setup an email server for our clients.  So they would
> have one server for their websites and one server for their
> email.  The following is the minimum of what I need for it.
> 
> 1.  Control Panel for each domain so that the domain owner can add
> their own email addresses.
> 2.  Control Panel for each user that is added to a domain so that
> they can change their own passwords if they want.  Also so that there
> can be a link to a program like Squirrelmail that we would install on
> the server.  I only want one copy of Squirrelmail if possible so that
> copies don't have to be installed for each domain.  The program
> Squirrelmail can be another program, but it would be nice if it was
> Squirrelmail because I know and like it.
> 3.  Control Panel for the main Admin to add the domains that will be
> on the server.
> 4.  Virtualization so that each domain can have an "admin" or "steve"
> if they want as their logins.
> 5.  Must run on a RHEL ES 4 or 3 server.
> 6.  MailScanner/SpamAssassin with a virus scanner.  For a normal
> installation of a server, I can install these with no problem.  It
> doesn't have to be MailScanner/SpamAssassin if there is something
> else that would work just as well and is as easy to manage/learn.  A
> virus scanner for all incoming and outgoing email is a must and no
> solution will work if it can't do this.
> 
> My main problem is that the solutions that I find won't fit the bill
> because of one or more of the following:
> 1.  Can't install the program, Control Panel, on our own server.
> 2.  Cost to much
> 3.  Has a monthly charge to use it
> 4.  Want a per domain charge, which would again...cost to much since
> we have about 1000 domains.
> 5.  Won't work as just an email server.  It wants to be the whole
> hosting solution and at the moment, we don't want that and can't
> change the Ensim control panels that we have now.  We are going to
> stick with the Ensim control panel for the web hosting but need to
> move the email off to a separate server because of the load on the
> server due to 10's of thousands of emails that our clients get and
> receive daily.
> 
> A free solution would be the best option if available since the
> majority (about 95%) of our clients are low end and don't pay much
> more than $20US a month.  VPOPmail
> http://www.inter7.com/index.php?page=vpopmail is a nice solution, but
> it only runs on qmail and, if possible, I would rather use sendmail.