[ih] Reporter query on the history of greater-than in quoted replies

[Jack Haverty]

My recollection is that the ">" convention began very early in the
history, probably 1972 +- a year or so.

At that time, I used a PDP-10 running ITS (MIT-DM).  Incoming mail was
appended to a file in your directory.  Outgoing mail was usually
prepared in an editor (Emacs or TECO) and dropped into a directory where
the mailer could pick it up and send it.

Since there were no ARPANET standards for forwarding, replying,
redirecting, or otherwise dealing with a message that had already been
sent and received, people invented their own conventions.

E.G., in replying or forwarding, several conventions were popular.
Sometimes the "old" message was indented.  Sometimes it had each line
prepended with some character such as - + = | >. Sometimes it was just
appended to the "new" message, with some kind of separator (line of ====
for example).   Sometimes your new text was interspersed inline with the
old.  You create your new message, possibly containing (pieces of) one
or more older messages from your inbox, and wrote the new message as a
file accessible to the mailer for delivery.

Various TECO and Emacs macros were quickly written to make this easier.
E.G., a macro could easily take the old message in your edit buffer and
put a > at the beginning of each line.  I imagine the ">" approach won
out when someone eventually chose it and locked its use into code inside
a "mail program" that was less easily modifiable by mere users.

I recall struggling with this situation when I was building a
"communications daemon" that attempted to deal sensibly with forwarded
and replied-to incoming messages.  There were simply too many personal
conventions being used to make it possible to write code to figure out
exactly what was going on in all the structure of an incoming message
that might contain parts of prior messages.

The headers were especially gnarly - e.g., trying to figure out who
originally sent a message that had been forwarded.

That led to the creation of the "MESSAGE-ID" header field, in an attempt
to get a "hook" into the protocol to make such things possible in the
future.  The "new protocol" was supposed to take care of all this.  We
never got there....

/Jack Haverty