Testing SMTP over IPv6

[Peter Tattam]

On Wed, 1 Dec 1999, Matt Crawford wrote:

> > If you are mixing IPv4 & IPv6 servers in the MX list,  it is important that
> > the MX list be set in the following manner...
> > 
> > IPv6 only servers		MX    a
> > IPv6 + IPv4 servers		MX    b
> > IPv4 only servers		MX    c
> > 
> > Where a < b < c
> 
> No, this sort of ordering is only important if not all the servers
> can do "final delivery" (i.e., take the message out of the SMTP
> world).
> 

By definition, MXs that are greater than the the mininmum would not remove mail
messages from the SMTP world.  If they don't have v6 access, the mail will
queue indefinitely, or possibly bounce if it can't reach any MX's that are
lower.  I am uncertain as to whether how an SMTP server would interpret an MX
list that had pointers to AAAA or A6 records in them.  Anyone have any ideas? 
Would they simply remove those names from the list resulting in truncated MX
list?  

Peter

--
Peter R. Tattam                            peter@trumpet.com
Managing Director,    Trumpet Software International Pty Ltd
Hobart, Australia,  Ph. +61-3-6245-0220,  Fax +61-3-62450210