DMARC report notifier

DMARC report notifier is a headless periodic handler of DMARC aggregate reports. In contrast to other solutions to DMARC report monitoring that pursue elaborate web dashboards designed to guide an organization through policy rollouts and infrastructure changes, this utility is intended to fill the gap for low-volume senders with already aligned infrastructure that just need to do the minimum due diligence of being alerted to unexpected problems.

Intended to be scheduled as a daily job, this uses parsedmarc to read DMARC reports from a specified IMAP folder and then move them to an archive in the same mailbox. If any reports indicate a problem, a notification is sent via Matrix.

Example notification:

⛔ 1 message blocked

Count	Sender	SPF	DKIM	DMARC	Reporter
1	IP: 192.0.2.1 rDNS: example.com Envelope: example.com Header: example.com	⛔ example.com: pass	⛔ example.com: pass	⛔	Example

✅ 12 messages allowed

Count	Sender	SPF	DKIM	DMARC	Reporter
6	IP: 192.0.2.2 rDNS: example.com Envelope: example.com Header: example.com	✅ example.com: pass	✅ example.com: pass	✅	Example
3	IP: 192.0.2.3 rDNS: example.com Envelope: example.com Header: example.com	✅ example.com: pass	✅ example.com: pass	✅	Example
2	IP: 192.0.2.3 rDNS: example.com Envelope: example.com Header: example.com	✅ example.com: pass	✅ example.com: pass	✅	Example
1	IP: 192.0.2.4 rDNS: example.com Envelope: example.com Header: example.com	✅ example.com: pass	✅ example.com: pass	✅	Example

Configuration:

• Incoming reports:
  • IMAP_HOST: parsedmarc imap.host
  • IMAP_USERNAME: parsedmarc imap.user
  • IMAP_PASSWORD: parsedmarc imap.password
  • IMAP_FOLDER_PROCESSED: parsedmarc mailbox.reports_folder
  • IMAP_FOLDER_UNPROCESSED: parsedmarc mailbox.archive_folder
• Outgoing notifications:
  • NOTIFICATION_LEVEL: level of DMARC failure to report (INFO/WARN/ERROR)
  • MATRIX_HOMESERVER_URL: base URL of Matrix client-server API
  • MATRIX_ACCESS_TOKEN: secret access token of user to send notifications from
  • MATRIX_ROOM_ID: room ID to send notifications to
• Schedule:
  • SCHEDULE: Supercronic cron expression
  • TZ: Supercronic time zone