https://calomel.org/pflogsumm.html

These systems use Postfix as the MTA:

• Virtualmin
• Zimbra

apt-get install pflogsumm

yum install postfix-perl-scripts

Needs verification and expansion

Print today's summary to the console:

nice -n 19 pflogsumm -d today /var/log/maillog | more

Generate log summary for yesterday:

perl /usr/sbin/pflogsumm -d yesterday /var/log/maillog

Use cron to send mail log summary at AM 1:00 everyday to root:

00 01 * * * /usr/bin/perl /usr/sbin/pflogsumm -e -d yesterday /var/log/maillog | mail -s 'Logwatch for Postfix' root