[Mailman-Developers] Author_is_list option in upcoming mailman 2.1.16

[Stephen J. Turnbull]

Franck Martin writes:

 > Unfortunately z= and especially l= are not used practically by
 > senders because they create a risk. One could add an attachment
 > containing malware to the message for instance.

Indeed, we have to assume that the MUAs are broken in this respect.
See Daniel Gillmor's posts on the problems MUAs have with indicating
which parts of a message are signed MIME parts in the "testing MUAs"
thread.

The basic state of the art seems to be that MUAs can't handle anything
safely except a signature that applies to the whole message.