rmail-mbox-format

rmail-mbox-format is a variable defined in `rmail.el'.
Its value is

mboxrd

Documentation:
The mbox format that your system uses.
There is no way to determine this, so you should set the appropriate value.
The formats quote lines containing "From " differently.
The choices are:
`mboxo' : lines that start with "From " quoted as ">From "
`mboxrd': lines that start with ">*From " quoted with another ">"
The `mboxo' format is ambiguous, in that one cannot know whether
a line starting with ">From " originally had a ">" or not.

It is not critical to set this to the correct value; it only affects
how Rmail displays lines starting with ">*From " in non-MIME messages.

See also `unrmail-mbox-format'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.