[Mailman-Users] header/footer attachments

[Mark Sapiro]

Christopher Adams wrote:
>
>I think you misunderstood me. I didn't mean that the header and/or footer
>was added to other attachments.


It wasn't clear to me whether you thought that or not.


>Typically, what happens  is that  list subscribers attach a PDF or Word
>document, using Outlook or Groupwise mail.


Which will normally result in Mailman receiving a message with MIME
structure as follows:

multipart/mixed
    multipart/alternative
        text/plain
        text/html
    application/pdf  (or application/msword)

Mailman will add a footer to this as a separate part and the result
will look like:

multipart/mixed
    multipart/alternative
        text/plain
        text/html
    application/pdf  (or application/msword)
    text/plain  (the footer)


>All the lists have a standard
>footer set by default. Many times they send in HTML format, even when they
>think they are sending in plain text, as that is what it appears like to
>them. In my experience with Outlook and based on information from previous
>list messages here, if a message with PDF or Word attachment is sent in
>plain text or HTML to a list with a footer set in Mailman, the message will
>come across with the document attached as well as a separate footer
>attachment.


Essentially correct although I prefer the term 'MIME part' over
'attachment'


>If no document is attached, regardless of the mail format, the
>footer will appear in the message. However, yahoo mail handles it normally
>and Thunderbird includes a footer attachment, but also displays it.
>
>I guess I was surprised that I hadn't figured out that it depended on
>whether a document was attached.


If the message is just text/plain, Mailman will normally add the footer
to the end if the text/plain message and the result will be a simple
text/plain message with the footer at the end.

However if the message is for example multipart alternative with a
structure like:

multipart/alternative
    text/plain
    text/html

Mailman will add the footer as follows:

multipart/mixed
    multipart/alternative
        text/plain
        text/html
    text/plain  (the footer)

i.e., it will create a multipart/mixed message with the original
message as the first part and the footer as the next part. As you note
above, how that looks when viewed with a particular MUA/email client
depends on the users MUA settings and the MUAs own notions of how this
structure should be rendered.


>So, I will put that one to rest.
>
>I also am wondering how much other mailman administrators and list owners
>make use of the built-in content filtering. As I understand it, if content
>filtering is activated and say, for example,  text/plain is added to 'Remove
>message attachments that have a matching content type', any footer that is
>attached should be removed.


And so will the text/plain message body! 

Also, content filtering can't remove Mailman's headers and footers
because they haven't been added yet at content filtering time (see
below for more).

>Again, based on the description of
>content-filtering, in the 'filter_action' option, "This action is not taken
>if after filtering the message still contains content. In that case the
>message is always forwarded on to the list membership" means that any
>message body would be delivered and only the attached footer would be
>dropped.


No. If filtering removes all the content, there is no message left and
nothing will be delivered.

I think your confusion arises from the notion of 'attachment', which is
an MUA notion, not a MIME notion. Filtering applies to MIME parts, not
just 'attachments'. There is really no way to determine from the MIME
structure of a message which part is the message 'body' and which
parts are 'attachments'.

There is no way in Mailman to filter out just those text/plain parts
which are attachments from those which are the message body.

Besides, this whole discussion is moot because headers and footers are
added after content filtering is completed.

-- 
Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan