🚀 go-pugleaf

The following two problems apply to sendmail.el, emacs version 18.58.1 .

1) If a file being written to by mail-do-cc is being visited by a
buffer, but the buffer is read-only, it fails to append and returns an
error.  I believe it should temporarily make the buffer writeable instead.

2) mail-do-cc always writes a "\n" before the "From" at the beginning
of the message.  When the file being written is previously empty or
nonexistent, this creates a mail file that begins with a blank line
before the first "From ", which is nonstandard and makes some mail
programs unable to recognize it a unix mail file.