Frank Perske via Mailman-users writes:
Here are excerpts from the email sent to the LIST-request address: (sent by Outlook/Exchange)
Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 MIME-Version: 1.0
DQo=
Eh, that's just a base64-encoded carriage return character (0x0D), What's in the subject?
And here is the response:
Omitted since I couldn't make sense of it.
This does not appear to be base64-encoded UTF-8.
It does appear to be base64-encoded UTF-8, that is the decoders I have conveniently available happily decode that as base64, autodetect UTF-8, and decode it to a string of characters. It does not appear to be doubly-encoded text in any language. Yes, it's mostly REPLACEMENT CHARACTER (U+FFFD), but it decoded as that code point, that's not the UTF-8 decoder replacing garbage in the input.
Does anyone have any idea how to fix this?
It would help if you gave us reason to believe Mailman has something to do with it. In the container setup, there should be a Postfix MTA, not sure what else, between the outside world and Mailman. Based on the information you provide, it's quite possible it never got to Mailman but was bounced by Postfix (or by Exchange for that matter).
We'd like to see the subject headers. Were those the entire message texts? It may be helpful to see Mailman-specific headers (most headers beginning with List- or X- but not X-Spam). Received headers showing that Mailman received the first and sent the second. Log messages from Mailman, the Postfix in the Mailman container, and from Exchange might help (especially if there are Python errors and backtraces from Mailman). What other software is in the path between Exchange/Outlook, including Postfix, spamcheckers, virus checkers, DKIM signing and verifying software, etc) and Mailman, in both directions? How and on what devices were these messages captured? What languages is Mailman configured to serve? What is the default language? Does the end-user's Mailman account have a language preference?
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan