Viktor Dukhovni:
> On Wed, Jan 08, 2020 at 09:36:48AM +0100, Thierry Fournier wrote:
>
> > > - An "smtp_nexthop_override_maps" feature that replaces the domain
> > > in the delivery request with one or more domain names. You decide
> > > the order of names in the result, and if the original domain
> > > should be part of the result. Specify [name], [name] to get
> > > comparable control as with your synthetic MX records.
> >
> > I like this idea, but it add a little bit of complexity for
> > understanding configuration.
>
> Which can also easily be done in your DNS resolver, including specifying equal
> weight or strictly ordered preferences.
>
> > > - Or, add support for multiple next-hop destinations in "relayhost",
> > > "transport_maps", and "default_transport". This changes the syntax
> > > and semantics of existing Postfix features. Again, specify [name],
> > > [name] to get comparable control as with your synthetic MX records.
> >
> > I like this idea.
>
> I am not convinced this is warranted.
I am leaning towards usability, i.e. allow multiple nexthops in
transport maps, relayhost, and default_transport. It is the more
natural way to express these things than doing stuff in DNS
or introducing yet another configuration mechanism.
As for purity, the reason I stuck with single nexthops was scheduler
fairness, but that has never worked for multiple domains that resolve
to the same MX hosts.
If we must implement true fairness we must change the qmgr/delivery
agent interface, and I estimate that having multiple nexthops would
not fundamentally make a difference.
Wietse
