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[Ralph Ballier <address@concealed>]

Hi Harri,

I did a bit more experimenting and then found a working solution.

I added the following two lines to /etc/sympa/sympa.conf:

dmarc_protection.mode dmarc_reject, dmarc_quarantine

dmarc_protection.phrase list_for_name

In /etc/postfix/smtp_header_checks, the following two lines ensure that the string X-Original-From: is replaced with Reply-To::

/^Reply-To:/ IGNORE

/^X-Original-From:\s*(.*)/ REPLACE Reply-To: $1

Best regards,

Ralph

Am 29.03.2025 14:55, schrieb Harri Suutari:

On 29/03/2025 14.51, Ralph Ballier wrote:

In Sympa, the workaround is to add "dmarc_protection.mode dmarc_reject" to sympa.conf.
However, this causes all information about the original sender of the email to be lost, and the recipient can only reply to the list.

"Previous values of the From: header field and the DKIM signature are saved in an X-Original-From: and X-Original-DKIM-Signature: header fields for later inspection." - https://www.sympa.community/manual/customize/dmarc-protection.html

The syntax of new From: can be formatted differently. I prefer "name_email_via_list" which at least with Thunderbird shows clear information where the email actually came from.

See https://www.sympa.community/gpldoc/man/sympa_config.5.html#dmarc_protection :

"dmarc_protection.phrase

New From name format

• Format:
  • display_name - "Name"
  • name_and_email - "Name" (e-mail)
  • name_via_list - "Name" (via List)
  • name_email_via_list - "Name" (e-mail via List)
  • list_for_name - "List" (on behalf of Name)
  • list_for_email - "List" (on behalf of e-mail)

• Default:

  name_via_list

• Context:

  list (config), domain (robot.conf), site (sympa.conf)

This is the format to be used for the sender name part of the new From header field."

How can I restore the sender's address in the header so that the recipient can reply directly to them?

Try setting the Reply address to 'user'. Maybe you have it set to 'list' currently?

It's a pity that many receiving SMTP servers still do not check and respect the ARC signature chain.