Receive and send emails in python

Here is a very simple example:

import smtplib

server = 'mail.server.com'
user = ''
password = ''

recipients = ['[email protected]', '[email protected]']
sender = '[email protected]'
message = 'Hello World'

session = smtplib.SMTP(server)
# if your SMTP server doesn't need authentications,
# you don't need the following line:
session.login(user, password)
session.sendmail(sender, recipients, message)

For more options, error handling, etc, look at the smtplib module documentation.

I do not think it would be a good idea to write a real mail server in Python. This is certainly possible (see mcrute's and Manuel Ceron's posts to have details) but it is a lot of work when you think of everything that a real mail server must handle (queuing, retransmission, dealing with spam, etc).

You should explain in more detail what you need. If you just want to react to incoming email, I would suggest to configure the mail server to call a program when it receives the email. This program could do what it wants (updating a database, creating a file, talking to another Python program).

To call an arbitrary program from the mail server, you have several choices:

1. For sendmail and Postfix, a ~/.forward containing "|/path/to/program"
2. If you use procmail, a recipe action of |path/to/program
3. And certainly many others

Found a helpful example for reading emails by connecting using IMAP:

Python — imaplib IMAP example with Gmail

import imaplib
mail = imaplib.IMAP4_SSL('imap.gmail.com')
mail.login('[email protected]', 'mypassword')
mail.list()
# Out: list of "folders" aka labels in gmail.
mail.select("inbox") # connect to inbox.
result, data = mail.search(None, "ALL")

ids = data[0] # data is a list.
id_list = ids.split() # ids is a space separated string
latest_email_id = id_list[-1] # get the latest

# fetch the email body (RFC822) for the given ID
result, data = mail.fetch(latest_email_id, "(RFC822)") 

raw_email = data[0][1] # here's the body, which is raw text of the whole email
# including headers and alternate payloads

Python has an SMTPD module that will be helpful to you for writing a server. You'll probably also want the SMTP module to do the re-send. Both modules are in the standard library at least since version 2.3.