Disposition-Notification-To: gets dropped

[deiKruve]

the "Disposition-Notification-To: " can be added from the web-protonmail.
However, when added in an external mail client it gets dropped by the bridge.

Expected Behavior

"Disposition-Notification-To: " should be send on to the mail receiver.

Current Behavior

"Disposition-Notification-To: " does not appear in the record of the sent mail message in the sent folder and is not received by the addressee.

Steps to Reproduce

send following mail message from the emacs mail client:
``
To: jan.de.kruyf@gmail.com
Subject: yourlousyperformance
From: jan de kruyf jan.de.kruyf@proton.me
Disposition-Notification-To: jan de kruyf jan.de.kruyf@proton.me
--text follows this line--
what are you on about.

dinges.
''

record of the mail in proton, see file :
pgp.txt

record of the mail received by gmail:
yourlousyperformance.txt

record of the log gotten with protonmail-bridge -l=trace --log-smtp 2> capture.log
capture.log

Version Information

https://proton.me

latest version of proton-bridge for linux from the proton web site.

jan@whimsey:~$ emacs --version
GNU Emacs 29.2
Copyright (C) 2024 Free Software Foundation, Inc.

Context (Environment)

I was setting up a cron job to gently prod some organisation to reply and/or collect proof of mails sent for the upcoming court case.

Help offered

If you point me to the file(s) involved I would be willing to read the code and see if I understand what goes on.

j.