Postfix helper script that does the following:

• make TLS mandatory for outgoing mail wherever possible and
• optionally alert postmasters of domains that don't support STARTTLS

In case of bugs, ideas, enhancements, feel free to open an issue or pull request on Github.

• Set Postfix SMTP client logging (configuration option smtp_tls_loglevel) to '1' or higher.
• Ensure that Python3 is installed.
• Copy the script to your mail system (e.g. to /usr/local/bin/) and make executable.
• Make sure that the script can write to Postfix TLS policy map and notls SQLite DB and that the directories exist.

• Configure the Postfix TLS policy map in main.cf:

smtp_tls_policy_maps = hash:/etc/postfix/tls_policy

• Run mail-tls-helper.py -h and learn about the commandline options.
• Optionally configure logrotate to run the script automatically against the mail log file just after rotation. This can be done by configuring a post-script in the corresponding logrotate configure include (e.g. /etc/logrotate.d/rsyslog):

/var/log/mail.log
{
	[...]
	postrotate
		[...]
		/usr/local/bin/mail-tls-helper.py -d example.org
	endscript
}

• munin: see the documentation header of munin-plugin

• 2018-07-18: version 0.9.0
  • added monitoring of mails sent over Tor
  • added reporting of blocked domains, because of missing TLS
  • added munin plugin
  • added tests
  • improved file handling
  • improved Python 3 compatibility
• 2017-11-11: version 0.8.1
  • fix version number and update todo list in the script
• 2017-11-11: version 0.8.0
  • restructured code, swap out all postfix related code into separate functions.
  • added new data structure 'relayDict' which can be filled by any mta specific functions
  • simplified the logic for parsing postfix logs
  • added IPv6 localhost address ::1 to relay whitlist
  • TLS domains are deleted from SQLite DB now
  • fixed calculated numbers of unencrypted mails
• 2017-06-04: version 0.7.3
  • add support for a relay whitelist
• 2017-06-04: version 0.7.2
  • set envelope sender address to op['from'] when using sendmail.
• 2017-05-18: version 0.7.1
  • don't send alert mails by default (Fixes #6)
  • consequently replace commandline options '-A'/'--no-alerts' by '-a'/'--alerts'.
• 2017-02-19: version 0.7
  • renamed to mail-tls-helper
  • complete rewrite in Python
  • fixed logfile parsing logic, much more robust now
  • added support for commandline arguments
  • added support to create a Postfix TLS policy map
• 2017-01-22: version 0.5
  • initial release