mailer.py

import dns.resolver
import socket
import ssl

FROM_ADDR = 'cynthia@example.com'
TO_ADDR = 'meow@example.com'

msg_helo = 'HELO msg\r\n'
msg_from = 'MAIL FROM:<{}>\r\n'
msg_rcpt = 'RCPT TO:<{}>\r\n'
msg_starttls = 'STARTTLS\r\n'
msg_quit = 'QUIT\r\n'
msg_data = 'DATA\r\n'
msg_content = """From: <{}>
To: <{}>
Date: Mon, 25 January 2019 4:20:00 -0000
Subject: {}

{}
.
"""

context = ssl.create_default_context()

def get_host(addr):
	parts = addr.split('@')
	mx = dns.resolver.query(parts[1], 'MX')
	for m in mx:
		print(m)
	return str(mx[0].exchange)[:-1]

def recv(s):
	d = s.recv(1024)
	print(d.decode('ascii'))
	return d

def send(s, msg):
	print(msg)
	s.send(msg.encode('ascii'))

def send_email(to_addr, from_addr, content, subject, use_starttls=False, port=25):
	to_host = get_host(to_addr)
	print(to_host)
	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	s.settimeout(2)
	s.connect((to_host, port))
	recv(s)
	send(s, msg_helo)
	recv(s)
	if use_starttls:
		send(s, msg_starttls)
		recv(s)
		s = context.wrap_socket(s, server_hostname=to_host)
	send(s, msg_from.format(from_addr))
	recv(s)
	send(s, msg_rcpt.format(to_addr))
	recv(s)
	send(s, msg_data)
	recv(s)
	send(s, msg_content.format(from_addr, to_addr, subject, content))
	send(s, msg_quit)
	s.close()

send_email(TO_ADDR, FROM_ADDR, 'hi', 'hello')