Aside: This may be the first time that I've responded to a Debian bug -- I expected that when I clicked on reply, I'd be given a text box on the bug report web page to make my comment, instead, I'm apparently writing an email. I presume this will get to the right place.
Hmm, I probably should not respond to this as I cannot do a complete or maybe even an adequate job. I do know this. When mail is stored in an mbox file, From at the beginning of a line (admittedly with other requirements after the From) can indicated the beginning of an mbox header, which separates one email from another. A "real" mbox header has other stuff on that line that can and should be parsed and considered to determine if it really is an mbox header, but some software in the email chain typically escapes a From at the beginning of a line (by prefixing it with a >, iirc) to, well, distinguish it from an mbox header and make it easier on the mbox software somewhere in the chain. I'd hesitate to suggest that "feature" should be disabled, there are probably lots of places where that would cause a problem. I don't know if there is another solution.
