Here is a small post on how to setup pflogsumm on your CentOS mail server running Postfix.  It takes advantage of logrorate being called nightly by cron.

1. Install pflogsumm

# yum install postfix-pflogsumm

2. Run a test

# /usr/sbin/pflogsumm /var/log/maillog

3. Update /etc/logrotate.d/syslog.  Add the following:

 prerotate
    pflogsumm /usr/local/psa/var/log/maillog | mail -s "Postfix Log - `date`" [email protected]
 endscript

And little script to send you log hourly if you send over 100 emails per hour.
Make sure to add it to your hourly cron job.

 
#!/bin/sh

hour_now=$(date | awk '{print $2,"", $3, substr($4,0,2)}')
var1=$(grep "$hour_now" /usr/local/psa/var/log/maillog|pflogsumm)
if (( $(echo "$var1" | sed -n '/  delivered$/p' | tr -d '[:alpha:]') > 100 ));
then
echo $var1 | mail -s "Postfix Log - `date`" [email protected]
fi

after update if your outlook do not work on smtp port 587 make sure to change /etc/postfix/master.cf

from:
submission inet n – n – – smtpd -o smtpd_enforce_tls=yes -o smtpd_tls_security_level=encrypt …..
to:
submission inet n – n – – smtpd -o smtpd_enforce_tls=no -o smtpd_tls_security_level=may …..