This is a cheap hack to get incoming messages for lists.opendev.org
to sit in senders' deferral queues while we're working on moving its
mailing lists to the new server. The firewall rules for
review02.opendev.org are set up to reject connections on 25/tcp,
which causes connecting MTAs to wait and try again after some period
of time. Once we update the records to match the new server instead,
any queued deliveries should arrive normally.
Change-Id: I9e4db643f4bbf66bb19c6f33eff5f3556fbba24e
121f6ec0d1