[Mailman-Developers] Re: AppleMail and Mailman3 content filtering

On 4/21/20 2:15 AM, Mike Gabriel via Mailman-Developers wrote:

Hi all,

I have a special case in a 3.3.0 Mailman3 instance.

One of our users uses AppleMail and sends a mail with PDF attachment to a mailing list with the following settings in Postorius:

   [x] filter content [x] collapse alternatives [x] convert html to plaintext

However, the PDF is not getting delivered to the mailing list recipients. It gets stripped off.

I see the issue.

The mail structure of the original mail is this:

Summarized

multipart/alternative text/plain multipart/mixed text/html application/pdf text/html

So the issue is the Apple Mail user is composing the message in rich text (HTML) format and drags and drops the PDF in the middle of the message body. Apple Mail then makes the

multipart/mixed
    text/html
    application/pdf
    text/html

message part [1] and finally makes the text/plain alternative that doesn't include the PDF.

Since your content filtering is set to collapse alternatives, only the text/plain first alternative part goes to the list.

I'm not that familiar with Apple Mail, but there may be a way for the user to 'attach' the PDF rather than dropping it into the message body and that may work.

[1] This message part will actually be displayed as composed only by an Apple Mail client, but that's another issue - part of "if you don't ask to interoperate with anything outside the Apple ecosystem, everything will be fine".

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