คุณสมบัติของโปรแกรม · ความโปร่งใสของข้อมูล SMTP

def smtp_data(payload):
    if type(payload) is not bytes or len(payload) > 65536:
        raise ValueError("bounded bytes")
    lines = payload.split(b"\r\n")
    if any(b"\r" in x or b"\n" in x for x in lines):
        raise ValueError("CRLF lines required")
    stuffed = b"\r\n".join(
        b"." + x if x.startswith(b".") else x for x in lines)
    if stuffed and not stuffed.endswith(b"\r\n"):
        stuffed += b"\r\n"
    return stuffed + b".\r\n"