Jesper Holck via Mailman-users writes:
In Mailcow, I have under "Options" added 172.19.199.1/24 as a "Forwarding Host" with no spam filter. I hoped this would make Rspamd happy, but apparently not.
I suspect that option does not accept a mask that way. "Host" normally implies /32, and 172.19.199.1 is not where the message is apparently coming from:
HFILTER_HELO_BADIP (4.5) [172.19.199.4, 1]
Life would be a lot easier if these Docker-based packages would provide options for the private subnet, mask, and the range within, so that all of the cooperating packages could be on the same network. Security, yes, but as long as they're all containers on the same Docker host, IMO you need to be really paranoid to worry about an attacker pivoting from Mailman to Mailcow to World Domination in that environment.
I don't know how to see the exact contains, including headers, of this message, unfortunately.
Probably the simplest (but manual) way to capture exactly what Mailman is sending is to
- install Mailhog on the Mailman node
- configure it to listen on eg port 8025, and send to the same place as Mailman,
- redirect Mailman to send to Mailhog,
- copy the messages from Mailhog's queue to some other place for analysis,
- redirect Mailman back to wherever it was sending (local Postfix or Mailcow's Postfix),
- and then release the messages from Mailhog.
You can probably do the same thing with a Postfix prequeue milter, but that's somewhat more complicated (you'd need to write a short script for the milter). Mailhog is a canned solution with two parameters: listen port (8025 in my example) and outgoing SMTP host (as configured in mailman.cfg).
Everything being dockerized complicates the installation process but Docker isn't my department. ;-)
My understanding is that e.g. DKIM-headers should be provided my Mailcow, not by Mailman itself.
That is correct.
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan