> ...
> We need a _much_ better and clearer explanation. I
> still think you're
> trying to explain your proposed solution to a
> problem when you haven't
> yet explained what the actual problem is.
Okay, let me try to start from the beginning. The
"normal" way how mails are delivered to closed
networks like VPNs is through a firewall which is
acting as a relay. This relay forwards mails coming
from the internet to a server inside the VPN or vice
versa.
FW A - VPN A with mailserver
/
the - FW B - VPN B with mailserver
internet \
FW C - VPN C with mailserver
The MX records in DNS point to the public firewall
interface and so on ... nothing special.
Now, what if customers B and C don't want to setup and
manage their mailserver on their own. They might have
mailboxes on a internet mail server (such as yahoo)
but that means that all his mail traffic would be
routed through the internet. Another opportunity would
be to let a provider setup a private mailserver being
part of the VPN. Instead of setting up a dedicated
mail host for each VPN the provider finally wants to
offer some kind of a virtual private mailserver. This
means on host which behaves like many separate
mailservers.
FW A - VPN A with mailserver
/
the - FW B - VPN B - PX B - virtual private
internet \ / mailserver
FW C - VPN C - PX C
This means e.g. that a mail send from [EMAIL PROTECTED]
to [EMAIL PROTECTED] should be delivered localy. If
[EMAIL PROTECTED] sends a mail to [EMAIL PROTECTED]
the mailserver should forward the mail through
firewall FW B to the internet. And finally, if
[EMAIL PROTECTED] send a mail to [EMAIL PROTECTED] the
mail should again be at first routed through FW B to
the internet and then transfered through FW C to the
private mailserver of VPN C (which is actually the
same server as the private server of VPN B).
I know this looks pretty confusing at first sight.
However, the advantage is that one can make full use
of the firewall functionallity of FW B and FW C (for
virus scans etc.) This would not be possible if the
server treats mail from one VPN to another as local.
Thanks for your patience
Peter
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