def foldfix(msg):
    """
    in_header = True
    buf = ''
    outmsg = ''
    for line in msg.split('\n'):
        if len(line) == 0:
            in_header=False

        if in_header:
            if line.endswith(':') and ' ' not in line:
                buf = line
                continue
            else:
                if buf:
                    line = buf + line
                    buf = ''
        outmsg += line + '\n'
    return outmsg