On Feb 27, 2015, at 11:46 AM, Murray S. Kucherawy wrote:
How absurd would it be to propose a flag for Mailman that would take your first case (non-MIME, or single-part text/plain) and convert it to a multipart/mixed with a child part of the original text/plain, and then apply the algorithm you have?
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What I'm worried about with such a design is the trivial text/plain message. Obviously merely appending the footer destroys any hope of validating only the original content. We'd have to entertain the idea that Mailman would make the simple message into a multipart/mixed + text/plain, then append the footer part and sign that; the verifier would drop the footer and then strip off the MIME to see if it can verify the original signature that way. That seems like its easy to get wrong, though it's likely to be a very common case.
The biggest downside, and probably the main reason we append the footer text in the text/plain-compatible-charset case is because of crappy MUAs. I think we *still* get complaints about the MIME composition not being rendered very well. Their MUAs will show them attachments without the message content they actually care about.
I wish I could say "fix the MUAs" but that's probably been futile since the day email was invented. ;)
That said, it's not a totally unreasonable suggestion. I wonder if it makes sense to have that be a user option (then, what's the default, what a standard says, or whatever minimizes user complaints).
Cheers, -Barry