Dave T?ht:
> d...@teklibre.org (Dave T?ht) writes:
>
> One unanswered question from this series of emails:
>
> >> Dave Taht:
> >
> > Would you take a patch that would let a crazed administrator disable
> > *sending* mail on different protocols?
> >
> > The simplest version would implement something like:
> >
> > smtp_try_sendprotocol: all, ipv4, ipv6
> >
> > A more complex version would let you specify the protocols your
> > configuration would try.
> >
> > smtp_try_sendprotocol_my_networks: all, ipv4, ipv6
> > smtp_try_sendprotocol_my_relays: all, ipv4, ipv6
> >
>
> Maybe there's a way to do this already...
Postfix sorts the remote SMTP server IP addresses by MX preference,
which are numbers in the range 0..32767. The next step is to avoid
backup MX loops: for this, the Postfix SMTP client must remove all
MX addresses that have the same of worse preference than Postfix's
own IP address.
To give preference for IPvX over IPvY, it is sufficient to tweak
those preference numbers. For example, one could multiply the MX
preferences by 2, then add 1 if the address belongs to the less
preferred protocol. With this, Postfix can still correctly avoid
backup MX loops (the address elimination becomes a little trickier,
though).
Wietse
