How to set/override header_checks.pcre

[whoo]

Hello,

I am looking for a way to save changes made in header_checks.pcre.
Currently, I use the volume mapping "./mail-data/dms/config/header_checks.pcre:/etc/postfix/maps/header_checks.pcre".

However, I'm seeking a more elegant solution for this.

Thank you.

[polarathene]

Could you expand on what you'd like?

Bind mounts - Directory vs Files

The problem with a file bind mount like you've mentioned is that changes will not propagate when the inode changes on the host system (or not persist from the container IIRC).

Directory mounts work better in that regard, so if you don't want to alter the other configs in that maps folder of the container, then mounting to a different location and adjusting the Postfix config to use the file from that folder instead could work better.

Automatic update via change detection event for configs in DMS Config Volume

If you're wanting support with our change detection service like other config files in the DMS config volume have, this would detect updates to the file from your DMS config volume and copy it over to the internal location. This usually will also trigger a reload of services like Postfix for ensuring the config update is acknowledged, but is not ideal for config files that are changing frequently as this can incur some minor downtime of a few seconds each time change detection is triggered.

If change detection support is what you'd like, I have previously provided some guidance to understand how we've implemented support. You just need to add the file into the monitor list, and then the logic to run cp when this config has a change detected. If you're comfortable doing trying that and it works for you feel free to contribute a PR.

Manually update within the container

Usually these configs don't change too often after the initial setup, if you anticipate that will be the same for you perhaps you only need the much simpler solution which is to docker exec -it dms-container-name bash and then you can edit the file with nano /etc/postfix/maps/header_checks.pcre, make some changes then CTRL + X to exit and save the changes, then run the command postfix reload and Postfix should apply the config update for you to test.

That's much simpler for experimenting and avoids the hassle of a custom build/contribution to our change detector support for one-off setup/troubleshooting changes.

---

Some related issues/discussions for reference:

• bug report: List-Unsubscribe not working #4224 (comment)
• https://github.com/orgs/docker-mailserver/discussions/4303#discussioncomment-11732892
• https://github.com/orgs/docker-mailserver/discussions/4542#discussioncomment-14087524

[whoo]

Thank you for the reply.
I want to add to the header... so adding parameter in header_checks.pcre works
/^Subject: .*(order from).*/ BCC sales_team@domain

But I would like to set it permanently as a user configuration and not have to do it manually after a down/up.

[polarathene]

If it's just the one header addition, you already have that solution?:

I am looking for a way to save changes made in header_checks.pcre.
Currently, I use the volume mapping "./mail-data/dms/config/header_checks.pcre:/etc/postfix/maps/header_checks.pcre".

Are you asking for support in the DMS Config Volume, to avoid the extra volume mount? Or something else?

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I provided you a few links before (1, 2) that demonstrate a solution with our user-patches.sh feature:

#!/bin/bash

RULE='/^Subject: .*(order from).*/     BCC sales_team@domain'

echo "${RULE}" >> /etc/postfix/maps/header_checks.pcre

[whoo]

Thank you,
Sounds a good way to avoid mapping.