This is a bit of an odd question, and I don't see an obvious way to do
this, but perhaps there's a non-obvious way.
We're looking to try Postfix out in some queues that would benefit
from Postfix's throttling and rate-limiting features, and I'm trying
to model this after our current qmail implementation, or at least get
a fairly similar setup working. We currently have our own internal
mail "router" that splits inbound mailing list messages based on both
sender and destination. It then directs the message(s) to the
appropriate qmail instance via qmqp.
We run multiple qmail instances on each host, and each instance
listens on a different qmqp port and also has different config
parameters (outgoing IP, remote concurrency).
I've had no issues with the qmqpd server in Postfix, but I'm trying to
figure out a way to route mail to a different transport based on which
qmqpd listener the message came in on. In other words, if I've got
multiple qmqp listeners on ports 628 through 640, I want to map
messages from each listener to a specific outbound smtp transport. If
a message comes in on a qmqp listener on port 628, I want it to use
"transport1", if it comes in on the listener on port 629, I want it to
use "transport2". Each transport would have a different outgoing IP,
different concurrency settings, etc. I would like to avoid running
multiple full instances of Postfix because I think having one shared
queue will likely perform better.
Any ideas on how to accomplish this?