smtprelaytest.py is a simple script to be run from the command-line that will test a mail server to see if it is an open relay. It will output color coded responses from the mail server as it just simply tests whether or not you can relay mail given the specified HELO name, sender and recipient. It also supports this test using STARTTLS. This is basically just a shortcut to using netcat or telnet.

You can either download it using this link or copy it from below.

#!/usr/bin/env python
 
__cvsversion__ = '$Id: smtprelaytest.py,v 1.3 2008/01/07 17:41:23 jay Exp $'
__author__ = 'Jay Deiman'
 
import smtplib , os , sys , getopt , socket , re
 
class TerminalController:
    """
    Author of the TerminalController class: Edward Loper
    Code copied from: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/475116
 
    A class that can be used to portably generate formatted output to
    a terminal.  
 
    `TerminalController` defines a set of instance variables whose
    values are initialized to the control sequence necessary to
    perform a given action.  These can be simply included in normal
    output to the terminal:
 
        >>> term = TerminalController()
        >>> print 'This is '+term.GREEN+'green'+term.NORMAL
 
    Alternatively, the `render()` method can used, which replaces
    '${action}' with the string required to perform 'action':
 
        >>> term = TerminalController()
        >>> print term.render('This is ${GREEN}green${NORMAL}')
 
    If the terminal doesn't support a given action, then the value of
    the corresponding instance variable will be set to ''.  As a
    result, the above code will still work on terminals that do not
    support color, except that their output will not be colored.
    Also, this means that you can test whether the terminal supports a
    given action by simply testing the truth value of the
    corresponding instance variable:
 
        >>> term = TerminalController()
        >>> if term.CLEAR_SCREEN:
        ...     print 'This terminal supports clearning the screen.'
 
    Finally, if the width and height of the terminal are known, then
    they will be stored in the `COLS` and `LINES` attributes.
    """
    # Cursor movement:
    BOL = ''             #: Move the cursor to the beginning of the line
    UP = ''              #: Move the cursor up one line
    DOWN = ''            #: Move the cursor down one line
    LEFT = ''            #: Move the cursor left one char
    RIGHT = ''           #: Move the cursor right one char
 
    # Deletion:
    CLEAR_SCREEN = ''    #: Clear the screen and move to home position
    CLEAR_EOL = ''       #: Clear to the end of the line.
    CLEAR_BOL = ''       #: Clear to the beginning of the line.
    CLEAR_EOS = ''       #: Clear to the end of the screen
 
    # Output modes:
    BOLD = ''            #: Turn on bold mode
    BLINK = ''           #: Turn on blink mode
    DIM = ''             #: Turn on half-bright mode
    REVERSE = ''         #: Turn on reverse-video mode
    NORMAL = ''          #: Turn off all modes
 
    # Cursor display:
    HIDE_CURSOR = ''     #: Make the cursor invisible
    SHOW_CURSOR = ''     #: Make the cursor visible
 
    # Terminal size:
    COLS = None          #: Width of the terminal (None for unknown)
    LINES = None         #: Height of the terminal (None for unknown)
 
    # Foreground colors:
    BLACK = BLUE = GREEN = CYAN = RED = MAGENTA = YELLOW = WHITE = ''
 
    # Background colors:
    BG_BLACK = BG_BLUE = BG_GREEN = BG_CYAN = ''
    BG_RED = BG_MAGENTA = BG_YELLOW = BG_WHITE = ''
 
    _STRING_CAPABILITIES = """
    BOL=cr UP=cuu1 DOWN=cud1 LEFT=cub1 RIGHT=cuf1
    CLEAR_SCREEN=clear CLEAR_EOL=el CLEAR_BOL=el1 CLEAR_EOS=ed BOLD=bold
    BLINK=blink DIM=dim REVERSE=rev UNDERLINE=smul NORMAL=sgr0
    HIDE_CURSOR=cinvis SHOW_CURSOR=cnorm""".split()
    _COLORS = """BLACK BLUE GREEN CYAN RED MAGENTA YELLOW WHITE""".split()
    _ANSICOLORS = "BLACK RED GREEN YELLOW BLUE MAGENTA CYAN WHITE".split()
 
    def __init__(self, term_stream=sys.stdout):
        """
        Create a `TerminalController` and initialize its attributes
        with appropriate values for the current terminal.
        `term_stream` is the stream that will be used for terminal
        output; if this stream is not a tty, then the terminal is
        assumed to be a dumb terminal (i.e., have no capabilities).
        """
        # Curses isn't available on all platforms
        try: import curses
        except: return
 
        # If the stream isn't a tty, then assume it has no capabilities.
        if not term_stream.isatty(): return
 
        # Check the terminal type.  If we fail, then assume that the
        # terminal has no capabilities.
        try: curses.setupterm()
        except: return
 
        # Look up numeric capabilities.
        self.COLS = curses.tigetnum('cols')
        self.LINES = curses.tigetnum('lines')
 
        # Look up string capabilities.
        for capability in self._STRING_CAPABILITIES:
            (attrib, cap_name) = capability.split('=')
            setattr(self, attrib, self._tigetstr(cap_name) or '')
 
        # Colors
        set_fg = self._tigetstr('setf')
        if set_fg:
            for i,color in zip(range(len(self._COLORS)), self._COLORS):
                setattr(self, color, curses.tparm(set_fg, i) or '')
        set_fg_ansi = self._tigetstr('setaf')
        if set_fg_ansi:
            for i,color in zip(range(len(self._ANSICOLORS)), self._ANSICOLORS):
                setattr(self, color, curses.tparm(set_fg_ansi, i) or '')
        set_bg = self._tigetstr('setb')
        if set_bg:
            for i,color in zip(range(len(self._COLORS)), self._COLORS):
                setattr(self, 'BG_'+color, curses.tparm(set_bg, i) or '')
        set_bg_ansi = self._tigetstr('setab')
        if set_bg_ansi:
            for i,color in zip(range(len(self._ANSICOLORS)), self._ANSICOLORS):
                setattr(self, 'BG_'+color, curses.tparm(set_bg_ansi, i) or '')
 
    def _tigetstr(self, cap_name):
        # String capabilities can include "delays" of the form "$<2>".
        # For any modern terminal, we should be able to just ignore
        # these, so strip them out.
        import curses
        cap = curses.tigetstr(cap_name) or ''
        return re.sub(r'\$<\d+>[/*]?', '', cap)
 
    def render(self, template):
        """
        Replace each $-substitutions in the given template string with
        the corresponding terminal control string (if it's defined) or
        '' (if it's not).
        """
        return re.sub(r'\$\$|\${\w+}', self._render_sub, template)
 
    def _render_sub(self, match):
        s = match.group()
        if s == '$$': return s
        else: return getattr(self, s[2:-1])
 
# Functions
def getHostName():
    fqdn = re.compile(r'^(?:[^\s\.]+\.){1,}(?:[^\s\.]+)$')
    res = socket.gethostbyaddr('127.0.0.1')
    if fqdn.match(res[0]):
        return res[0]
    for name in res[1]:
        if fqdn.match(name):
            return name
 
def usage(exitCode=0):
    print '%s -r <remote host> [-p <port>] ' % os.path.basename(sys.argv[0]) + \
            '-c <recipient> [-f <send from>] [-t <helo name>]'
    print """
    -h,--help            Help, what you are looking at
    -s,--usetls          Use TLS for the connection
    -r,--remhost=        Remote hostname or IP
    -p,--port=           Remote host port
    -t,--helo=           HELO hostname.  An attempt will be made to determine
                         the hostname if not supplied
    -c,--recip=          The recipient email address to use
    -f,--from=           The email address that the request should come
                         from.  "test@qwest.net" will be used by default
    """
    sys.exit(exitCode)
 
def gAndR(code):
    code = int(code)
    if code >= 200 and code < 300:
        return "${GREEN}"
    else:
        return "${RED}"
 
# Config vars
remoteHost = ''
remotePort = 25
heloHost = getHostName()
mRecip = ''
mFrom = 'test@qwest.net'
useTls = False
 
# Get the command line opts
shortOpts = 'hsr:p:t:c:f:'
longOpts = ['help' , 'usetls' , 'remhost=' , 'port=' , 'helo=' , 
            'recip=' , 'from=']
try:
    optList , junk = getopt.getopt(sys.argv[1:] , shortOpts , longOpts)
except getopt.GetoptError , e:
    print e
    usage(1)
for opt , val in optList:
    if opt in ('-h' , '--help'):
        usage()
    elif opt in ('-s' , '--usetls'):
        useTls = True
    elif opt in ('-r' , '--remhost'):
        remoteHost = val
    elif opt in ('-p' , '--port'):
        remotePort = int(val)
    elif opt in ('-t' , '--helo'):
        heloHost = val
    elif opt in ('-c' , '--recip'):
        mRecip = val
    elif opt in ('-f' , '--from'):
        mFrom = val
# If we don't have a remoteHost or recipient, usage and exit
if not remoteHost or not mRecip:
    usage(1)
 
# Now, establish the connection and try the relay
t = TerminalController()
s = smtplib.SMTP()
print 'Connecting to %s:%d' % (remoteHost , remotePort)
resp = s.connect(remoteHost , remotePort)
print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
print 'HELOing as %s' % heloHost
resp = s.helo(heloHost)
print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
if useTls:
    print 'Starting a TLS connection'
    resp = s.starttls()
    print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
mailFrom = 'MAIL FROM: <%s>\r\n' % mFrom
print 'Sending: %s' % mailFrom.strip()
s.send(mailFrom)
resp = s.getreply()
print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
mailTo = 'RCPT TO: <%s>\r\n' % mRecip
print 'Sending: %s' % mailTo.strip()
s.send(mailTo)
resp = s.getreply()
print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
print 'Sending: QUIT'
s.send('QUIT\r\n')
resp = s.getreply()
print t.render('%s%d %s${NORMAL}' % (gAndR(resp[0]) , resp[0] , resp[1]))
s.close()

Using smtprelaytest.py -h on the command line produces the following:

$ ./smtprelaytest.py -h
smtprelaytest.py -r <remote host> [-p <port>] -c <recipient> [-f <send from>] [-t <helo name>]

    -h,--help            Help, what you are looking at
    -s,--usetls          Use TLS for the connection
    -r,--remhost=        Remote hostname or IP
    -p,--port=           Remote host port
    -t,--helo=           HELO hostname.  An attempt will be made to determine
                         the hostname if not supplied
    -c,--recip=          The recipient email address to use
    -f,--from=           The email address that the request should come
                         from.  "test@qwest.net" will be used by default

A typical lookup, with TLS support would look like this:

# ./smtprelaytest.py -s -r 127.0.0.1 -f admin@splitstreams.com -c admin@splitstreams.com
Connecting to 127.0.0.1:25
220 mail.splitstreams.com ESMTP Postfix
HELOing as localhost.splitstreams.com
250 mail.splitstreams.com
Starting a TLS connection
220 2.0.0 Ready to start TLS
Sending: MAIL FROM: <admin@splitstreams.com>
250 2.1.0 Ok
Sending: RCPT TO: <admin@splitstreams.com>
250 2.1.5 Ok
Sending: QUIT
221 2.0.0 Bye