Re: mutt mbox format for new mailboxes

On Thu, May 15, 2025 at 02:25:44PM -0700, Will Yardley wrote:

>It's interesting that in replies, Mutt uses >From escaping, though in
>the actual raw mbox file, it's not present.

No, you're confusing two different uses of '>' at the beginning of a line.

A reply can quote the original message, and when it does, and the reply 
is plain text, then each line of the quoted text is preceded with '>', 
to mark it as a quote. This convention originated in Usenet, long ago. 
It has nothing to do with file formats.

You can see that in this message: in your text, quoted above, each line 
is preceded with '>'.

">From " quoting is part of mbox file format, done to...well, read this:
<http://www.panix.com/~kh/mailstorage/>

>This page:
>https://www.loc.gov/preservation/digital/formats/fdd/fdd000383.shtml
>has some details.
>https://www.loc.gov/preservation/digital/formats/fdd/fdd000386.shtml
>mentions MBOXCL and MBOXCL2 dating back to SYSVr4. So, if that's the
>case, that may have been the widely understood "mbox" used well before
>Mutt was first written?

Sure.

     mboxo               1974
     Berkeley mbox       1978?
     mboxcl2             SYSVr4, 1985?
     Rahul Dhesi mbox    1995

The Library of Congress stuff you cite above, and what it links to[1], 
are correct, except they leave out the Berkeley variant. There have 
also been many other minor variants, done for not much reason.


[1] 
<https://web.archive.org/web/20161023162432/jdebp.eu/FGA/mail-mbox-formats.html>