Re: [exim] Routing failed deliveries through an ESP

> put the ip addresses in ignore_target_hosts instead.

Excellent suggestion! That option does exactly what my lookup is doing in a
much more reliable and efficient manner. I had glossed over that option
because its documentation describes in so much detail the handling of IP
addresses, I assumed it wasn't suited for wildcard host names. Never
underestimate Exim! To which, let me take a moment to praise the folks
behind Exim for such comprehensive documentation. Exim is a sophisticated
piece of software and the documentation is every bit as impressive.

> you can detect rejections using event_action
> arranging for the not-smtp ACL to return "drop"

You gave me good food for thought, and after some trial and error I was
able to implement exactly what I intended using a shell script and some
strategic ${run} calls. It's opened a whole world of possibilities
including something I've had an eye towards implementing - message event
webhooks.

I use a transport event_action to run a script to capture message events
and DSN messages. I can then conditionally add a header to the
bounce_message_file that acl_not_smtp can evaluate to drop the bounce,
which in turn freezes the original message. All very straightforward.

One side-effect I'm curious about is the error message logged when a bounce
message is dropped.

> Error while reading message with no usable sender address: rejected by
non-SMTP ACL: local configuration problem

Any chance there's a "less problematic" way to drop a bounce? :) If I
implement a webhook based mechanism to report bounces, it would be nice to
not fill mainlog with this message. (I unset log_reject_target to keep the
headers out of rejectlog but mainlog still gets a report.)

Thanks!
Lance