[Mailman-Users] MIME "mulitpart/mixed boundary" re-arrangement causes digital signature to fail

[Donald Wong]

Is it possible to make mailman leave the entire content of a message 
with untouched (example, multipart MIME messages)

The Problem:
When trying to send a digitally signed (SSL cert) email to a Mailman 
list, using Mozilla Thunderbird in this case, the recipients on the list 
would see the signature as Not Valid.  We've pinpointed the problem to 
that Mailman would parse the entire email message and re-arrange the 
MIME header/content, thus rendering the signature invalid.  What Mailman 
would change is to strip the newline character that's in between 
"Content-Type:..." and "boundary", as the "Content-Type:multipart/mixed" 
header with newline is added by Thunderbird when attaching a file 
attachment (including vcard).  While either having or not having the 
newline will conform to RFC MIME specifications(or so I was led to 
believe) thus making it a correct behaviour in that sense, it's 
definitely wrecking the signature.

Example:
Content-Type: multipart/mixed; boundary="------------digitsdigits"

I've also tried to test with Outlook Express and it would produce the 
same result.

So I think the easiest way to solve this is somehow configure Mailman to 
not rearrange the message while processing the message.

On the server side, we're using Mailman 2.1.5 on a Fedora Core 3 system, 
and the mailman rpm is the one built by redhat.