Ralph Seichter:
> Hello list,
>
> I am trying to configure Postfix to process inbound mail in the following
> manner:
>
> 1. A sender connect to Postfix smtpd to deliver a message.
>
> 2. Postfix calls Milters A, B, C. Each of these Milters can either (a)
> reject the message, (b) accept the message without changes or (c) add
> a new header "X-SomeHeader: SomeValue" and then accept the message.
>
> 3. If any of the milters rejects the message (case 2a) Postfix rejects
> the delivery attempt in progress with code 5xx.
>
> 4. In case 2b (all milters accept without changes) Postfix signals 250
> to the sender, terminates the inbound connection, looks up a "next hop"
> transport and passes the message to that destination.
>
> The tricky part is case 2c. Messages marked with one or more additional
> Headers, and only these messages, need to be passed to a fourth milter D
> after a delay (!) of somewhere between 90s and 5m (current estimate).
> Milter D then either accepts the message as is or adds yet another new
> header before accepting.
>
> As calling milter D depends on the presence and content of headers, I
> assume that it might be difficult to achieve the desired behaviour with
> built-in Postfix features of a single Postfix instance. I am currently
> exploring the idea of writing a transport service which FIFO-queues all
> inbound messages for case 2c, delaying them for X seconds before passing
> them to a second Postfix instance which talks to milter D.
>
> However, I'd rather use Postfix's own robust mechanisms (perhaps the
> deferred queue?) instead of implementing a queing transport from scratch.
> Also, I estimate that whatever queue I use will grow to hold approx. 1-5
> million messages at peak times, so performance and robustness are key.
>
> If you have ideas that could help me solve this, I'd appreciate you
> letting me know.
What problem are you trying to solve? Please describe the problem
(why not deliver mail when it is received), not the solution (labeling
a message, and diverting labeled messages).
Wietse
