[Mailman-Users] Admin Approval Emails Not Sent

[DT]

Mailman version 2.1.16
Installed via apt-get
Server OS is Ubuntu 14.04.3 LTS
MTA is postfix version 2.11.0

When a user subscribes to the email list, an approval email is not being
sent to the admins/moderators.  The variables admin_immed_notify and
admin_notify_mchanges are set to yes.  The subscribe requests are getting
picked up during the daily cron job and an email is then sent at 8:00 AM.

Test emails to -owner work internally from postfix and when sent externally
from gmail.

Here's a link to all the log file snippets from the time of the subscribe
request:
https://gist.github.com/dmofot/c367151ba262f476c2c6

Any ideas where to start troubleshooting this issue?

DT