Is the ">" part of your preprocessor?
Nope - where did you get that from? Here's my original message (is your
mailer adding that?)
The > in front of the F could have been added anywhere in the mail stream.
Orginating MUA, any MTA's involved, or the final reader. Most likely it
was the delivering MTA.
Many mail readers (ie, old /bin/mail and /usr/ucb/mail) determine the first
line of a mail message by looking for a line that begins with "From". So,
to prevent mail content from being interpreted as the start of a mail
message, any lines in the body of a mail message that starts with "F" is
escaped so it starts with ">F". It's a mechanism that has been around for
probably as long as sendmail.
This is, of course, a holdover from the days before the Content-Length:
One eventually learns to read ">F" as "F" ;->