I just had a problem on a Mailman 2.1.5 list although I think it's the Python email library - Python is 2.3.3.
A mal formed MIME message was posted to a list. The message was much larger than max_message_size yet it wasn't held, and several parts came through that weren't in pass_mime_types.
The basic post was multipart/mixed with a multipart/alternative sub part, a message/rfc822 sub part and the final text/plain msg_footer.
The message/rfc822 sub part was multipart/mixed with 3 subparts of type multipart/alternative, application/pdf and multipart/appledouble.
The problem with the MIME structure is that the boundary for the multipart/alternative and multipart/appledouble sub parts of the multipart/mixed message/rfc822 was identical to the boundary of the multipart/mixed part. I suspect the original message/rfc822 attached message was malformed, but it could have been broken in the attaching process. The original attached message was created by User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.0.6 and the post was sent by Yahoo mail.
I suspect what happened is that the Python email library saw the end of part boundary for the second multipart/alternative part and treated it as the end of the message/rfc822 part since the boundary was the same.
Thus the big parts didn't get counted in the message size nor did they get filtered by content filtering.
Is this analysis correct? Is it fixed in later versions of the email library?
Here is an annotated copy of the received post with all content and non-relevant headers removed.
Received: from [63.201.34.79] by web81402.mail.yahoo.com via HTTP; Fri, 16 Sep 2005 16:32:37 PDT MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="0-95218806-1126913557=:91474" Content-Transfer-Encoding: 8bit X-Content-Filtered-By: Mailman/MimeDel 2.1.5 X-BeenThere: gpc-talk@grizz.org X-Mailman-Version: 2.1.5 -------------------above from the headers of the received post
--0-95218806-1126913557=:91474 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit ------------------above are first part headers - I think this was originally multipart/alternative and a text/html part was stripped
--0-95218806-1126913557=:91474 Content-Type: message/rfc822 ------------------part headers from the attached message/rfc822 part
User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.0.6 Mime-version: 1.0 Content-type: multipart/mixed; boundary="MS_Mac_OE_3209732028_3749601_MIME_Part" Content-Length: 175299 ------------------from the headers of the attached message
--MS_Mac_OE_3209732028_3749601_MIME_Part Content-type: multipart/alternative; boundary="MS_Mac_OE_3209732028_3749601_MIME_Part" ---------------------part headers for multipart/alternative sub part of attached message. Note that the boundary is the same as that of the containing multipart/mixed part.
--MS_Mac_OE_3209732028_3749601_MIME_Part Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit -------------------------part headers for text/plain alternative
--MS_Mac_OE_3209732028_3749601_MIME_Part-- -----------------------end of multipart/alternative part but also looks like end of multipart/mixed part. I think a text/html part may have been stripped, but the multipart/alternative part isn't collapsed.
--MS_Mac_OE_3209732028_3749601_MIME_Part Content-type: application/pdf; name="Recruitment.pdf"; x-mac-creator="4341524F"; x-mac-type="50444620" Content-disposition: attachment Content-transfer-encoding: base64 -----------------------------------another sub part of multipart/mixed
- should have been filtered
--MS_Mac_OE_3209732028_3749601_MIME_Part Content-type: multipart/appledouble; boundary="MS_Mac_OE_3209732024_3737509_MIME_Part" -----------------------------------another sub part of multipart/mixed
- should have been filtered. Still same boundary
--MS_Mac_OE_3209732024_3737509_MIME_Part Content-type: application/applefile; name="High Sierra Trip 2003 Me" Content-transfer-encoding: base64 Content-disposition: attachment ----------------------sub part of multipart/appledouble should have been filtered
--MS_Mac_OE_3209732024_3737509_MIME_Part Content-type: image/jpeg; name="High Sierra Trip 2003 Me"; x-mac-creator="6F676C65"; x-mac-type="4A504547" Content-disposition: attachment Content-transfer-encoding: base64 ----------------------sub part of multipart/appledouble should have been filtered
--MS_Mac_OE_3209732024_3737509_MIME_Part-- ----------------------- end of multipart/appledouble
--MS_Mac_OE_3209732028_3749601_MIME_Part-- ------------------------ end of multipart/mixed
--0-95218806-1126913557=:91474 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline ------------------------ part headers for list footer
--0-95218806-1126913557=:91474-- ------------------------ end of outermost message
-- Mark Sapiro msapiro@value.net The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan