On Wed, May 18, 2011 at 2:30 PM, evilgh...@packetmail.net <evilgh...@packetmail.net> wrote: > > I'm certainly open for any suggestions for accommodating my goal of applying > an > IPv4 relayhost to non-IPv6 capable traffic if there is such a way to > accomplish > this goal with the existing configuration directives. >
What if you do this: eliminate the ability of your mail server to send SMTP over IPv4, possibly by removing any IPv4 address from it, or firewalling that ability away. Set up fallback_relay on this host so that all mail that did not make it on the first try goes to your relay host. There will be *some* IPv6 capable traffic sent that way as the result of transient failures, but it will be mostly messages that require IPv4.
