Public bug reported:
Mailman tarballs contain a Defaults.py file with this configuration:
DEFAULT_PASS_MIME_TYPES = ['multipart/mixed','multipart/alternative','text/plain']
NOTE: I don't know how this file is generated, I found it on the tarballs but not on the repository
So, when someone enables filtering on a mailing list by mime-type, the default is to filter all emails not matching any of those 3 mime-types.
This list of default mime types allowed misses to include "multipart/signed".
Therefore, this is unfortunately filtering any "multipart/signed" emails.
"multipart/signed" is defined on RFC 3156 https://tools.ietf.org/html/rfc3156 and is the recommended way of signing mails with GPG. See http://wiki.gnupg.org/SignatureHandling
The proposed change is to modify that default configuration to:
DEFAULT_PASS_MIME_TYPES = ['multipart/mixed', 'multipart/alternative', 'multipart/signed', 'text/plain', ]
This default causes trouble to people that signs their mails with GPG. I already had problems due to this default on the Alioth Debian mailing lists and on the WebKit mailing lists because the admin enabled filtering by mime-type and didn't changed the default.
Please, change this default by adding at least 'multipart/signed' to the list of types allowed.
** Affects: mailman Importance: Undecided Status: New