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

mouss mlist.only at free.fr
Tue Oct 23 16:18:51 UTC 2007

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.

just to add that the virtual aliases way is to be preferred.
transport_maps is a "latency sensitive" map, so it is better not to use
an rdbms for that.

More information about the CentOS mailing list