Viktor Dukhovni:
> On Tue, Nov 29, 2022 at 09:59:47AM -0500, Wietse Venema wrote:
>
> > In /etc/postfix/master.cf:
> > ==========================
> >
> > smtp1 unix - - n - - smtp
> > -o { smtp_bind_address = 1.2.3.1 }
> > -o { smtp_helo_name = helo-for-1.2.3.1 }
> >
> > smtp2 unix - - n - - smtp
> > -o { smtp_bind_address = 1.2.3.2 }
> > -o { smtp_helo_name = helo-for-1.2.3.2 }
> >
> > In /etc/postfix/main.cf:
> > ========================
> >
> > Next an example that supports different warming up ratios for
> > different destinations. See "Notes" below for a simpler approach
> > when the warming up ratios can be the same for all destinations.
> >
> > This example uses a nested table, which requires a restriction class.
> > smtpd_recipient_restrictions = check_recipient_access
> > inline:{
> > { gmail.com = class-gmail }
> > { yahoo.com = class-yahoo }
> > }
> > ...other restrictions...
> >
> > # To get (90%, 10%), specify one filter 9x and the other filter 1x.
> > # The order does not matter.
> > restriction_classes = class-gmail, class-yahoo
> > class-gmail = check_recipient_access randmap:{filter smtp1:, filter
> > smtp2:}
> > class-yahoo = check_recipient_access randmap:{filter smtp1:, filter
> > smtp2:}
>
> I didn't suggest approaches based on FILTER because they may not work
> correcly with multi-recipient mail, when not all recipients share the
> same domain part. "FILTER" is message level, not per-recipient.
>
> Problems would in practice be rare, but perhaps all the harder to
> understand and debug if/when they arise.
And only when different domains have very different warming-up
requirements.
> A semantically sound solution here would be a table that selectively
> (and using a random weight) replaces some MX host names with an
> alternative relay.
>
> This would be a new feature, to support sending sites that are migrating
> existing high volume outbound relays to a new location or upstream IP
> provider.
Indeed, the proposed examples assume that all IP addresses can in
some way be made available to one Postfix instance.
To warm up a remote IP address, one would use:
class-gmail = check_recipient_access randmap:{filter smtp1:, filter
smtp2:host:port}
class-yahoo = check_recipient_access randmap:{filter smtp1:, filter
smtp2:host:port}
Where host:port specifies a remote Postfix relay.
Wietse
