Re: mutt mbox format for new mailboxes

On Fri, May 16, 2025 at 04:04:35PM -0400, Rich Kulawiec wrote:

>We referred to them as "mboxes" back in the day; the term was so 
>common that some programs used "mbox" as a default filename. (Can't 
>recall offhand, but maybe the early BSD version of the "mail" command, 
>AKA "ucbmail"?)

I think the filename came first, and later the file format was named 
after that. I think "mbox" was the default name for a file in the 
user's home directory. When the user fired up a mail reader, it moved 
new messages from the system file where the MTA put them, say 
/var/mail/freduser, to ~freduser/mbox. And I do seem to think that came 
from BSD.

>But since some standard is (usually) better than no standard, and it looks
>to me like RFC 4155 was well-researched, it's probably worth using as a
>reference.

Nope, sorry. RFC 4155 has a problem. Its default format, the only one 
it defines, defines the From_ line rigidly, forbids ">From " escaping, 
and does not use a length. It says messages should be found by 
recognizing the whole From_ line, with exact syntax.

That fails when the message body includes such a From_ line, as it 
might when people use email to discuss mbox format, as here. Like this:

 From [email protected] Thu Jan  1 00:00:00 1970

An RFC 4155 reader would take that line above as the beginning of a new 
message, and would fail to read the rest of this message.

Far as I know, that RFC 4155 format has never been implemented. I think 
it's best to keep it that way. I say, continue to ignore that RFC.