[CentOS] Large scale Postfix/Cyrus email system for 100,000+ users

[Christopher Chan]

> What I am having a problem is how do I get postfix to transfer the
> email to the particular IMAP server that the user account is on.  I
> know that I need to use lmtp and transport, but all the examples I
> have seen show forwarding all email to 1 IMAP server.  I would like
> Postfix to do a lookup for each mailbox and determine which IMAP
> server to deliver it to.
> 
> Anyone have a working example that they could share?  It would be
> greatly appreciated.

Sorry, never did lmtp but if I read your post properly, you want to do a 
transport map lookup for each mailbox to get the correct lmtp entry.

I suggest using cdb for your transport map database and rebuilding it 
say every eight hours. cdb offers fast lookup and database building. You 
can store the entries in mysql and dump to a file for cdb creation. I do 
not suggest mysql for transport even if you are using mysql connection 
pooling and transport tables get called in a lot of places.