Bounced Email Service separates incoming bounced emails in temporary failures and permanent failures (also called as soft and hard bounces) and handles messages accordingly.
- The undeliverable emails (bounced emails) are forwarded from the HPI mailservers to the postfix
mailserver on our router (
router-{a,b}.oob.xopic.de). - The mailserver is configured to send the bounced emails to an amqp message
queue running on the Bounced Email Service.
- add the domains which should be handled to
/etc/postfix/main.cftomydestination = ..., openhpi.de, opensap.info: - add to
/etc/aliasestheno-replyuser:no-reply:|/usr/local/bin/send_message_to_rabbitmq.sh - create the file
/usr/local/bin/send_message_to_rabbitmq.shwith:
- add the domains which should be handled to
#!/bin/bash
exec amqp-publish -u amqp://<rabbitmq-user>:<rabbitmq-password>@<rabbitmq-server>/bouncedemails -r "bouncedemails"A SMTP server has been added to the Bounced Email Service. This means that
bounced emails can now be forwarded directly to the bouncedemails virtual
machine. However, the SMPT server can only be started on a high port (default:
2525). Therefore the sending HPI mailservers (mail4 and mail5) have to be
configured to this port. However, this requires that the HPI mailservers can
reach the bouncedemails virtual machine. If the HPI mail servers cannot be
configured to the high port, it is recommended to establish a corresponding
simpleproxy service.
- Bounced Email Service consumes the message queue. The message handler
separates the incoming bounced email and handles them accordingly:
- Temporary failure: The accused email address in the bounced email and the domain from which the originally email was sent are stored in a local database together with a counter. The counter is incremented with each new incoming occurence. Once the counter exceeds a configured threshold, the accordingly email address is treaten as a permanent failure (and the counter is resetted).
- Permanent failure: The accused email address in the bounced email is reported to the xikolo-account service. The xikolo-account service disables all notifications regarding this email address.
If the Bounced Email Service detects a permanent failure, then the
responsible plattform will be informed. The plattform is determined by the
no-reply address, e.g. no-reply@openhpi.de. The Bounced Email Service
tries to POST-request the plattform. The accordingly HTTP endpoint MUST be
defined in the config.yml. See bounced_email_service/config.template.yml.
The base_url endpoint MUST include {address} as an URL part. E.g.
"http://mydomain.de/emails/{address}/suspend"
As prerequisite you have to have installed: python3, python3-pip, rabbitmq-server.
Further you have to have installed pipenv.
- Create a vhost
bouncedemails - Create a user (e.g. bouncedemails) with password, with all permissions to the new created vhost
- run
pipenv install - copy
bounced_email_service/config.template.ymltobounced_email_service/config.ymland adjust the values for production stage. - fill the credentials in
bounced_email_service/config.yml
Install the systemd control files for Bounced_Email_Service. In the
resources folder are examples for the systemd files. Adjust the values and
install the services.
Start a local webserver by python3 tests/develop_webserver.py 7001. In another shell run the service
as bouncedemails user in forground by pipenv run python3 bounced_email_service/service.py --env develop --debug run.
In a 3rd shell send a testmail to rabbitmq-server by cat tests/testmail | tests/send_mail_to_rabbitmq.sh.
This should give the output:
root@bouncedemails:~# journalctl -f -u bouncedemails.service
bouncedemails - ------------- INCOMING MESSAGE -------------
bouncedemails - From: MAILER-DAEMON@mail2de.some-provider.com (Mail Delivery System)
bouncedemails - Subject: Undelivered Mail Returned to Sender
bouncedemails - To: no-reply@mydomain.de
bouncedemails - Domain: mydomain.de
bouncedemails - Permanent: evil-address@some-provider.com
bouncedemails - Response: 200 / {"processd_email": "evil-address@some-provider.com"}