Strange sendmail behaviour after upgrade to 9.1-BETA2

[J David]

On Wed, Jul 31, 2013 at 8:54 AM, Pavel Timofeev <timp87 at gmail.com> wrote:
> I've just installed new fresh 9.2-BETA2 amd64 on another machine.
> Same behavior - Sendmail asks DNS only for AAAA record of mx server.

We also noticed one of our machines suddenly started using IPv6 to
send outbound email (from Postfix rather than Sendmail) after it was
upgraded from 8.4 to 9-STABLE a bit ago.

I think there's been a change in the default IPv6 behavior between 8
and 9.  Probably one of the many important things in UPDATING that
always seems to slip past me.

We use IPv6 extensively, so we were pleased after the initial
surprise, but if you don't then ip6addrctl is probably the right
temporary answer until you do.