[OT] Re: What's the best possible email failover solution

[Lucas Holt]

Just a thought, but couldn't you write the imapd process to act more 
like a web application server in the RDBMS scenario.  You can cache 
data and limit the number of select statements executed on the actual 
data store.  Although one wouldn't have something like cookies for 
sessions, the username and other characteristics of the message could 
be used to create a hash identifying the data in the imap server.  Imap 
clients also tend to retrieve the headers only and then retrieve 
message bodies if someone "reads" the message.  For most clients, 
caching the headers might be a good idea.  Of course the timeout value 
couldn't be to large or they wouldn't get the newest messages in a 
reasonable time.

You could also seperate the cache from the imap daemon similar to how 
livejournal.com uses a seperate caching service to limit the overhead 
on the mysql servers for large mail deployments.  Its similar in the 
sense people want the most recent journal entries just like they want 
their new messages.

The other advantage to a mail server implemented as a database is that 
one could add groupwise type functionality as pluggable modules that 
tied in with the data store.  Its overkill, but could be rather neat.

Lucas Holt
Luke at FoolishGames.com
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