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

Christopher Chan christopher at ias.com.hk
Wed Oct 24 03:43:15 UTC 2007

Matt Shields wrote:
> Data changes too frequently to generate the file every x number of
> minutes across all smtp servers.

You have to support instantly deliverable mailboxes for new accounts?

> The mysql db isn't a single server.  It's a master (read/write) with
> multiple replicas for read access.  Those replicas are load balanced
> with LVS (heartbeat/ldirectord/ipvsadm).  The postfix(smtp) incoming
> and outgoing servers are also load balanced with LVS.  So database
> read speed is not an issue.  Believe me, we know how to build large
> high traffic sites, the only problem we're having is the exact syntax
> on using transport_maps or virtual_transport with multiple lmtp
> transports, and I think I got that figured out with the
> transport_maps.  Will post more later.

I assume that you are aware that transport_maps is called multiple times.

Recipient_maps in rdbms tables generate at least two lookups (one for 
smtpd, one for cleanup) but when you add transport_maps, that will at 
least explode to one per subdomain of the sender address (you can 
mitigate a lot of that with the domain setting in the map configuration 
file) as trivial-rewrite tries to build its triples for addresses.

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