Please add multipart/signed to DEFAULT_PASS_MIME_TYPES

Bug #1517446 reported by carloslp
This bug affects 1 person
Affects Status Importance Assigned to Milestone
GNU Mailman
Fix Released
Mark Sapiro

Bug Description

Mailman tarballs contain a 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 <> and is the recommended way of signing mails with GPG. See

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.

Related branches

Revision history for this message
carloslp (carloslp) wrote :

> The proposed change is to modify that default configuration to:
> DEFAULT_PASS_MIME_TYPES = ['multipart/mixed', 'multipart/alternative', 'multipart/signed', 'text/plain', ]

I mean:

DEFAULT_PASS_MIME_TYPES = ['multipart/mixed', 'multipart/alternative', 'multipart/signed', 'text/plain' ]

Revision history for this message
Mark Sapiro (msapiro) wrote :

The tarballs we distribute do not contain Mailman/ They and the lp:mailman/2.1 branch contain only Mailman/ Mailman/ is generated by configure by applying various configure options and defaults to Mailman/

Also, in Python,

DEFAULT_PASS_MIME_TYPES = ['multipart/mixed', 'multipart/alternative', 'multipart/signed', 'text/plain', ]


DEFAULT_PASS_MIME_TYPES = ['multipart/mixed', 'multipart/alternative', 'multipart/signed', 'text/plain' ]

(without the last comma) are equivalent.

Now, as far as the actual bug is concerned, I am unsure as to the best default for pass_mime_types. I agree that various multipart subtypes such as multipart/related and multipart/signed should be accepted so their text/plain sub-parts will be accepted. To this end, I think at a minimum we should have

DEFAULT_PASS_MIME_TYPES = ['multipart', 'text/plain']

to accept any text/plain subparts of any multipart type, but this brings up other questions. Namely, should we accept message/rfc822 parts to ultimately accept text/plain parts from attached (forwarded or ?) messages, and if we are accepting multipart/signed, should we also accept the actual signature.

For the former, I think the answer is yes. The latter is more complicated because application/pkcs7-signature parts are binary so in the spirit of only accepting text/plain, perhaps we should only accept application/pgp-signature signature parts. I'm tending towards

DEFAULT_PASS_MIME_TYPES = ['multipart', 'message/rfc822', 'text/plain', 'application/pgp-signature']

but I'm continuing to think about it.

Changed in mailman:
assignee: nobody → Mark Sapiro (msapiro)
importance: Undecided → Low
milestone: none → 2.1.21
status: New → In Progress
Mark Sapiro (msapiro)
Changed in mailman:
status: In Progress → Fix Committed
Mark Sapiro (msapiro)
Changed in mailman:
status: Fix Committed → Fix Released
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