What's the best possible email failover solution

[Bill Moran]

Lucas Holt <luke at foolishgames.com> wrote:

> Keep in mind that storing mail in a RDBMS as a backup requires an 
> efficient method to restore mail into your mail server's format.

I'm looking at RDBMS _being_ the native format.  Dovecot has this
on the TODO list, but it's low priority for that project.

If we use SQL as the native storage, then we duplicate the config
on both machines (i.e. the Postfix config and the IMAP server
config) and in the case of hardware failure, we just switch IP
addresses.  That can even be automated to happen without manual
intervention!

> Would it be possible to have a second mail server internal to your 
> network that would receive copies of the mail from the primary mail 
> server to store them as a backup?  This would be closer to real time 
> and for the most part would beat the 30 minute interval to do an rsync. 
>   In addition, if the system proved reliable you could rsync the 
> secondary at night and not have the primary down at all.

Doesn't really accomplish the goal.  The point is to have the IMAP
folders in two places at all times.  That way, when a user deletes
an email, its deleted in both places, when Postfix delivers an email,
it's delivered to both places, if a user moves an email from one
folder to another ... you get the idea.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com