On Jan 14, 2011, at 11:31 AM, Dave CROCKER wrote:
Can't decide on the right place to ask this question, so you folks got
A list member sends a message that contains a MIME body. (If it makes a
difference between a simple, since body that is MIME encoded, versus one that
has "attachments", then clarifying that is part of the exercise.)
The mail list adds a typical footer to the message and sends it out.
How does the footer related to the received MIME? Is a new MIME body
created? Is the footer added as a separate MIME attachment? Is the footer
somehow distinguishable from the original MIME content?
I'm trying to understand the nature of the violence done by a mailing list to
I've seen at least these variants:
1. Append a plain ascii footer to the end of the 822 body. (This ends up as a
non-displayed MIME postlude for any multipart message.)
2. Same as 1, but only do it for single part messages.
3. Append an additional text/plain mime section to the existing
multipart/mixed capsule (works well for mailing lists that are primarily
text/plain with attached files).
4. Create a new multipart/mixed message containing two parts, the first being
the entire (usually multipart/alternative) content of the inbound mail and the
second being a text/plain footer.
5. Modify the content of the existing text/html (and sometimes text/plain)
section, injecting the content into the existing mime part.
Number 5 is mostly used for advertising supported services, where they want to
make sure that the eyeballs will always see the injected content, and the
injected content wants to be text/html. It's painful to do compared with the
Most of the good discussion mailing list managers seem to use a hybrid,
depending on the inbound mail type. I think a common algorithm is:
text/plain => append a plain text footer to the existing content
multipart/mixed => add a new text/plain content-disposition=inline part to
the existing container
anything else => create a new multipart/mixed message containing the original
message and a new text/plain content-disposition=inline footer part.