John Spence wrote about finding a way to check that a piece of mail came
through a mailing list (in contrast to a personal copy of an item also posted
to a list), and enumerated the indicators he is using for the lists to which
he is subscribed, including,
| > | 3. nothing on 1 list that is manually administered :-(
| > Doesn't that manually-administered list rewrite the From_ line at least?
| > That's virtually indispensable.
And John responded,
| hmm.. time to display my ignorance here. I've just grepped my mail
| directory and the only instance of "From_" is in messages that you wrote.
| I did look for instances of "From_" in message headers after reading your
| answer but couldn't find any and assumed I was either blind or you made a
No, neither. The underscore there is not literal but intended as a stand-in
for a space. "The From_ line" means the line at the top of a letter that
begins "From<space>", often called "the Unix From".
You won't find a line beginning "From<underscore>", but we call it that to
distinguish it from the From: header (the RFC822 From). You see, if we said
simply "the From line" it could be that (1) we're talking about RFC822
headers and mean the From: line [and we didn't type the colon because it is
implicit in that context], or (2) we mean the From: line but accidentally
left out the colon in typing. Saying "From_" makes it unambiguous.