[Mailman-Users] mails without MIME delimiter break when sent through mailman

[Jan Lausch]

Dear all,

I've got a strange problem that I'd ask for help with. I tried to word it as easy I could.

Abstract:
Some MUAs send picture-attachments not seperated by MIME-delimiters, but by "begin" and "end". Mailman adding the list footer with a MIME-delimiter breaks these mails.


Detailed description: 
Since migrating a list to a new server (mailman 2.1.12), mails with attachments (pictures) coming from one of the subscribers come with the picture not as picture but as plaintext within the mail. However the same mail, sent directly (not over list) looks fine. It seems the extra MIME element (list footer) added by mailman, breaks the MIME set. As I said: with the old server (older mailman) this did not happen.


Let's look at the details:
 
Example what a broken mail looks like:
------------
This is the body of the email
blablabla
begin 666 examplepicture.jpg
M_]C_X `02D9)1@`!`0$`2 !(``#_X0_^17AI9@``34T`*@````@`"@$/``(`
M```&````A@$0``(````)````C $2``,````!``$```$:``4````!````E@$;
M``4````!````G@$H``,````!``(```$Q``(````$-BXQ``$R``(````4````
...
--------------

Facts:
- X-Mailer: Microsoft Outlook 14.0
- Other versions of Outlook / other MUAs work fine
- Before the migration (older mailman) all was working fine
- sending the same mail directly (not over mailman) will result in a decently visible mail
- there are interesting differences in the MIME-declarations

 
Let's try to figure this out and compare an email sent from another MUA to a broken one:
 
HEADER - WORKING MAIL OVER LIST
Content-Type: multipart/mixed;
	boundary="----=_NextPart_000_04C6_01CE4BF9.45807730"
X-Mailer: Microsoft Office Outlook 11
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157

HEADER - BROKEN MAIL OVER LIST
X-Mailer: Microsoft Outlook 14.0
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="===============1490256753484786707=="

------------------------------------------

BODY - WORKING MAIL OVER LIST
Envelope-To: XXXXX
This is a multi-part message in MIME format.
------=_NextPart_000_04C6_01CE4BF9.45807730
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

BODY TEXT HERE   XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

------=_NextPart_000_04C6_01CE4BF9.45807730
Content-Type: image/jpeg;
	name="DSC_0138 1024-50.jpg"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
	filename="DSC_0138 1024-50.jpg"

/9j/4AAQSkZJRgABAQEASABIAAD/2wBDABALDA4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkz

--------------------------------------------
 
BODY - BROKEN MAIL OVER LIST
Envelope-To: XXX
--===============1490256753484786707==
Content-Language: de

BODY TEXT HERE  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

begin 666 DSC_0138 1024-50.jpg
M_]C_X `02D9)1@

 END OF WORKING MAIL
PICTURE DATA
------=_NextPart_000_04C6_01CE4BF9.45807730
Content-Type: text/plain; charset="iso-8859-1"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
_______________________________________________
XXX mailing list
XXX at XXX.dehttp://lists.XXX.de/mailman/listinfo/XXX[https://3c.gmx.net/mail/client/dereferrer?redirectUrl=http%3A%2F%2Flists.XXX.de%2Fmailman%2Flistinfo%2FXXX&selection=tfol11c55a91759e2e2e]
------=_NextPart_000_04C6_01CE4BF9.45807730--


----------------------------------------

This is how the plaintext of a broken email ends:

[PICTURE DATA]
end
--===============1490256753484786707==
Content-Type: text/plain; charset="iso-8859-1"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
_______________________________________________
XXX mailing list
XXX at XXX.dehttp://lists.XXX.de/mailman/listinfo/XXX[https://3c.gmx.net/mail/client/dereferrer?redirectUrl=http%3A%2F%2Flists.XXX.de%2Fmailman%2Flistinfo%2FXXX&selection=tfol11c55a91759e2e2e]
--===============1490256753484786707==--

 
 
COMMENT

Obviously the jpeg isn't seperated by the delimiter here even though the delimiter is introduced in the header but instead the picture only has "begin" and "end".
I'm a bit confused: is "begin" and "end" a replacement for a MIME-delimiter?

Is that a correct MIME-set? But still this malformatted mail does work if sent directly to recipient (not via mailman) and still does NOT have the delimiter then. It only breaks when sent via mailman.
Obviously things stop working when mailman adds the delimiter consisting the msg_footer.
 
Does anyone have an idea on what to do?
 
Can I perhaps prevent mailman adding a footer if I leave "msg_footer" empty?
Is it still added (empty) or not at all?
 
Thanks for your help and thoughts!
 
Jan