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

[Ross S. W. Walker]

mouss wrote:
> 
> mouss wrote:
> > Matt Shields wrote:
> >> I'm trying to set up a large scale email system that 
> supports 100,000+
> >> IMAP accounts.  We have an existing frontend web interface 
> that does a
> >> lookup on a mysql db to figure out which IMAP server to 
> connect to for
> >> each user.  For the email infrastructure we have decided on Postfix
> >> and Cyrus.  We have configured both to use mysql to get the virtual
> >> user information.
> >>
> >> Because of the way that the infrastructure is (biz 
> reasons) we are not
> >> doing shared storage, we have numerous IMAP servers that 
> we distribute
> >> accounts across.  As we add more users, we image up a new 
> IMAP server.
> >>  For our business's scaling purposes this was the best plan.
> >>
> >> 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.
> > 
> > There are primarily two ways:
> > 
> > [virtual aliase]
> > you can use virtual_alias_maps to redirect foo at example.com to
> > foo at hostN.example.com, provided the final server accepts 
> such addresses.
> > 
> > If the final server doesn't accept these, and you use smtp 
> to relay to,
> > then you can write the addresses back, using smtp_generic_maps.
> > 
> > [transport]
> > an laternative is to use use (per-user) transport_maps. 
> something like
> > 
> > foo at example.com		relay:[hostN.example.com]
> > 
> > 
> > In bothe approaches, the mappings can be generated using 
> sql statements
> > (mostly CONCAT). something like
> > ...
> > query = SELECT concat('relay:[', host, '.example.com]')
> > 	FROM User
> > 	where '%u' = user and '%d' = domain
> > 
> > you get the idea I hope.

True, it may be better to just have a cron job dump out
new static maps every 15 minutes or so then to have the
MTA query on every delivery especially for 100K accounts.

-Ross

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