On Thu, Jun 16, 2022 at 07:35:20PM -0400, Wietse Venema wrote: > Bob Proulx: > > Is there a transport mapping equivalent to match against the MX host > > instead of against the the recipient address? That's really what is > > desired here. I didn't think such a feature existed yet. > > it would require a Postfix lookup table that returns MX hosts for > a domain, > > pipemap:{domain-to-mx, inline:{ {.google.com = slow:} } > > plus some safeguard to avoid doing this for local deliveries.
Transport resolutiont that does remote DNS lookups will be a prohibitive performance bottleneck on systems delivering a steady non-trivial stream of mail. The queue manager is not multi-threaded, and each recipient domain can/will incur some delay. I would not recommend doing this until (some nebulous day) the queue manager can perform asynchronous transport resolution for multiple recipients in parallel. -- Viktor.