Python smtplib proxy support

Question

I would like to send email through a proxy.

My current implementation is as follows:

I connect to the smtp server with authentication. After I've successfully logged in, I send an email. It works fine but when I look at the email header I can see my host name. I would like to tunnel it through a proxy instead.

Any help will be highly appreciated.

Solution 1

Use SocksiPy:

import smtplib
import socks

#'proxy_port' should be an integer
#'PROXY_TYPE_SOCKS4' can be replaced to HTTP or PROXY_TYPE_SOCKS5
socks.setdefaultproxy(socks.PROXY_TYPE_SOCKS4, proxy_host, proxy_port)
socks.wrapmodule(smtplib)

smtp = smtplib.SMTP()
...

Solution 2

I had a similar problem yesterday, this is the code I wrote to solve the problem. It invisibly allows you to use all of the smtp methods via proxy.

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#       smtprox.py
#       Shouts to suidrewt
#
# ############################################# #
# This module allows Proxy support in MailFux.  #
# Shouts to Betrayed for telling me about       #
# http CONNECT                                  #
# ############################################# #

import smtplib
import socket

def recvline(sock):
    stop = 0
    line = ''
    while True:
        i = sock.recv(1)
        if i == '\n': stop = 1
        line += i
        if stop == 1:
            break
    return line

class ProxSMTP( smtplib.SMTP ):

    def __init__(self, host='', port=0, p_address='',p_port=0, local_hostname=None,
             timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
        """Initialize a new instance.

        If specified, `host' is the name of the remote host to which to
        connect.  If specified, `port' specifies the port to which to connect.
        By default, smtplib.SMTP_PORT is used.  An SMTPConnectError is raised
        if the specified `host' doesn't respond correctly.  If specified,
        `local_hostname` is used as the FQDN of the local host.  By default,
        the local hostname is found using socket.getfqdn().

        """
        self.p_address = p_address
        self.p_port = p_port

        self.timeout = timeout
        self.esmtp_features = {}
        self.default_port = smtplib.SMTP_PORT
        if host:
            (code, msg) = self.connect(host, port)
            if code != 220:
                raise SMTPConnectError(code, msg)
        if local_hostname is not None:
            self.local_hostname = local_hostname
        else:
            # RFC 2821 says we should use the fqdn in the EHLO/HELO verb, and
            # if that can't be calculated, that we should use a domain literal
            # instead (essentially an encoded IP address like [A.B.C.D]).
            fqdn = socket.getfqdn()
            if '.' in fqdn:
                self.local_hostname = fqdn
            else:
                # We can't find an fqdn hostname, so use a domain literal
                addr = '127.0.0.1'
                try:
                    addr = socket.gethostbyname(socket.gethostname())
                except socket.gaierror:
                    pass
                self.local_hostname = '[%s]' % addr
        smtplib.SMTP.__init__(self)

    def _get_socket(self, port, host, timeout):
        # This makes it simpler for SMTP_SSL to use the SMTP connect code
        # and just alter the socket connection bit.
        if self.debuglevel > 0: print>>stderr, 'connect:', (host, port)
        new_socket = socket.create_connection((self.p_address,self.p_port), timeout)
        new_socket.sendall("CONNECT {0}:{1} HTTP/1.1\r\n\r\n".format(port,host))
        for x in xrange(2): recvline(new_socket)
        return new_socket

Solution 3

As mkerrig and Denis Cornehl noted in a comment on another answer PySocks create_connection with a modified SMTP class from smtplib works without having to monkeypatch sockets for everything.

I still hate this implementation (who know what will break with other version of python or smtplib), but this works for now (3.8.1). Since I was unable to find any other solutions elsewhere on the internet that worked, here is my attempt:

1. Copy the init and _get_socket functions from the smtplib.SMTP class
2. Modify init to add proxy_addr, and proxy_port
3. Modify _get_socket so that it returns a socks.create_connection() (vs socket)
4. Change SMTPConnectError to smtplib.SMTPConnectError so it works

my_proxy_smtplib.py:

import socket
import smtplib

import socks


class ProxySMTP(smtplib.SMTP):
    def __init__(self, host='', port=0, local_hostname=None,
                 timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
                 source_address=None, proxy_addr=None, proxy_port=None):
        """Initialize a new instance.

        If specified, `host' is the name of the remote host to which to
        connect.  If specified, `port' specifies the port to which to connect.
        By default, smtplib.SMTP_PORT is used.  If a host is specified the
        connect method is called, and if it returns anything other than a
        success code an SMTPConnectError is raised.  If specified,
        `local_hostname` is used as the FQDN of the local host in the HELO/EHLO
        command.  Otherwise, the local hostname is found using
        socket.getfqdn(). The `source_address` parameter takes a 2-tuple (host,
        port) for the socket to bind to as its source address before
        connecting. If the host is '' and port is 0, the OS default behavior
        will be used.

        """
        self._host = host
        self.timeout = timeout
        self.esmtp_features = {}
        self.command_encoding = 'ascii'
        self.source_address = source_address
        self.proxy_addr = proxy_addr
        self.proxy_port = proxy_port

        if host:
            (code, msg) = self.connect(host, port)
            if code != 220:
                self.close()
                raise smtplib.SMTPConnectError(code, msg)
        if local_hostname is not None:
            self.local_hostname = local_hostname
        else:
            # RFC 2821 says we should use the fqdn in the EHLO/HELO verb, and
            # if that can't be calculated, that we should use a domain literal
            # instead (essentially an encoded IP address like [A.B.C.D]).
            fqdn = socket.getfqdn()
            if '.' in fqdn:
                self.local_hostname = fqdn
            else:
                # We can't find an fqdn hostname, so use a domain literal
                addr = '127.0.0.1'
                try:
                    addr = socket.gethostbyname(socket.gethostname())
                except socket.gaierror:
                    pass
                self.local_hostname = '[%s]' % addr

    def _get_socket(self, host, port, timeout):
        # This makes it simpler for SMTP_SSL to use the SMTP connect code
        # and just alter the socket connection bit.
        if self.debuglevel > 0:
            self._print_debug('connect: to', (host, port), self.source_address)
        return socks.create_connection((host, port),
                                       proxy_type=socks.PROXY_TYPE_SOCKS5,
                                       timeout=timeout,
                                       proxy_addr=self.proxy_addr,
                                       proxy_port=self.proxy_port)

And to use:

from my_proxy_smtplib import ProxySMTP

email_server = ProxySMTP('smtp.gmail.com', 587,
                         proxy_addr='192.168.0.1',
                         proxy_port=3487)
email_server.starttls()
email_server.login(user_email, user_pass)
email_server.sendmail(user_email, recipient_list, msg.as_string())
email_server.quit()