realtime email backup across computer centers

[Stephan Poehlsen <20030513debian@poehlsen.net>]

Hi,

How would you realize a realtime email-backup across two different
computers in two different computer-centers?

Let's say I have a mail-server A in city A and a backup-mail-server B
in city B. So if an airplain crashs one computer-center, no email gets
lost.

I think all mail must be forwarded from server A to B (and must be
acknowledged from B) before server A acknowleges incomming mail.

Does there exists a solution? Maybe with qmail?

Stephan