Wez Furlong 7ac9a5eac0 smtp_dispatcher: handle pathologic all-452 case ...

Continuing in the same vein as 94628f06ab,
ensure that we have a reasonable outcome when a batch of size > 1
encounters 100% ambiguous 452 responses.

Without special consideration we'd end up in an infinite retry loop for
these, as we'd think that we'd hit the recpient limit on the connection
every time.

This commit introduces a small amount of state into the dispatcher so
that we can remember the set of (spoolid, recipient) from the prior
transaction on the session.

When deciding whether something is eligible for immediate retry
we will gate that choice on the current (spoolid, recipient) being
absent from the prior set of ids.  In this way, we bound the immediate
retry for a recipient to one per connection.

To make things a bit more robust when trying to decide whether a 452
means "too many recipients" or not, if we're not sure, we now call out
to the bounce classifier which can be configured to emit a
`TooManyRecipients` classification.  If the classifier produces either
that or some non-Uncategorized response, then we have a confident
assessment.  Otherwise, we're unsure and will factor that into the
retry strategy.

2025-11-07 08:13:36 +00:00

..

iana.toml

smtp_dispatcher: handle pathologic all-452 case

2025-11-07 08:13:36 +00:00