Good day,
I have recently installed mailman3 on a Debian trixie system.
While I managed to set up most of it (the mailing lists, postorius and also a working gateway to our inn2 news server) I'm seeing a weird duplication of messages, that seems to be related to the error messages posted below.
When I switch off gating to nntp the duplication stops. Also only mail messages are duplicated, not the postings on the news server.
Any pointers as to what to look into, or how to remedy this problem are greatly appreciated :)
Thanks,
Laurens
here come the error logs: Feb 23 20:39:08 2026 (2776528) ACCEPT: <e4938b85cbd75c0b04867514fc0b8ad9@betola.de> Feb 23 20:39:10 2026 (2776528) ACCEPT: <e4938b85cbd75c0b04867514fc0b8ad9@betola.de> Feb 23 20:39:12 2026 (2776530) <e4938b85cbd75c0b04867514fc0b8ad9@betola.de> NNTP error for test@grenzland.club Traceback (most recent call last): File "/usr/lib/python3/dist-packages/mailman/runners/nntp.py", line 94, in _dispose conn.post(fp) ~~~~~~~~~^^^^ File "/usr/lib/python3/dist-packages/nntplib/__init__.py", line 916, in post return self._post('POST', data) ~~~~~~~~~~^^^^^^^^^^^^^^ File "/usr/lib/python3/dist-packages/nntplib/__init__.py", line 909, in _post return self._getresp() ~~~~~~~~~~~~~^^ File "/usr/lib/python3/dist-packages/nntplib/__init__.py", line 492, in _getresp raise NNTPTemporaryError(resp) nntplib.NNTPTemporaryError: 441 Can't set system Injection-Info header field