Testing SMTP over IPv6

[Matt Crawford]

> ...  I would hazard a guess
> though that for at least 75% of cases the guidelines I suggested might apply.

Yes, or more.

> Anyone like to comment as to how sendmail will typically react in
> the suggested scenario?

Except in pathological cases (DNS answer > 8192 bytes, pinhead admin
configured "ignore truncation", or more than 100 MX records for
target) sendmail will try all the mail exchangers it should.  Your
guidelines would then "win".  Hm, except, does it need to be pointed
out that

> > > > > IPv6 only servers		MX    a
> > > > > IPv6 + IPv4 servers		MX    b
> > > > > IPv4 only servers		MX    c
> > > > > 
> > > > > Where a < b < c

should be c < b < a if the "final delivery" is made only on v4-only
hosts?
				Matt