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@xxxxxxxxxxx to
> foo@xxxxxxxxxxxxxxxxx, 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@xxxxxxxxxxx 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.
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