what should happen is that the sender gets a message back that says:
Your message could not be delivered because it was illegally formatted.
You should replace your mail reader with one that works correctly.
See http://foo.bar/mail-readers.html for a list of broken mail readers.
Noone would want to configure his server that way when it blocks
legitimate mail. And users of broken MUAs would still complain that
``only this server is so picky'', even if they agree that it's right.
yup. and like you say, it's a drawback to the robustness principle -
it encourages brokenness.
Keith