Re: [exim] Routing failed deliveries through an ESP

> I'm going to make the very obvious and morally correct answer: you don't.

I truly understand and at a basic level agree with that position. I'm
simply trying to balance that with what is analogous to a short-term
network outage. I need to have a failover in place to keep the business
functioning while I work to resolve the issue.

> why not just send via the ESP in the first place?

Cost savings. We'd prefer to pay the ESP to deliver only what it must and
let our server deliver most of the messages most of the time.

This is top of mind now because we're about to stand up a new server and I
won't have a good picture of the IP reputation until the bounces start
rolling in. It will take weeks to get everything running smoothly. In the
meantime, bounces will cause chaos :)

The alternative is to implement a process outside of Exim that monitors the
reject log and re-attempts delivery, skipping dnslookup, but I'm hoping the
right Exim router configuration will save us the (non-trivial) effort.

Thanks!
Lance