Python email

Sending emails in python uses at least two libraries.

1. an email message object (headers, body, attachments) is built
2. a library is used to send the message

email.message.Message

This object builds the body of an email message, the header, and any attachments.

You can construct a message using email.message.Message directly, but instead I'd recommend using a subclass from email.mime.* to get you off the ground faster.

Build a plaintext message

import email.mime.text

msg = email.mime.text.MIMEText('Hello Friend')  # mimetype: text/plain
msg['Subject'] = 'Greetings'
msg['To'] = 'user1@example.com'

Build an html message

import email.mime.text

msg = email.mime.text.MIMEText('Hello Friend', _subtype='html')   # mimetype:  text/html
msg['Subject'] = 'Greetings'
msg['To'] = 'user1@example.com'

Formatting To/Cc/Bcc

To/Cc/Bcc are written to the header as dictionary keys.

msg = email.mime.text.MIMEText('Hi')
msg['To'] = 'user1@example.com'
msg['Cc'] = 'user2@example.com'
msg['Bcc'] = 'user3@example.com'

The format of these headers should match RFC-2822 https://tools.ietf.org/html/rfc2822.html

• emails are comma-separated
• emails can be specified in two formats
  • jdoe@example.com
  • John Doe <jdoe@example.com>
• header fields exceeding XX characters should be wrap text onto following line using \r\n\t (RFC-2822 section-2.2.3)

msg['Bcc'] = (
    'john doe <john.doe@example.com,\r\n'
    '\tjane doe <jane.doe@example.com,\r\n'
    '\tuser@example.com'
)

sending email

smtplib

smtplib is used to communicate with an existing SMTP server to send your mail.

Connection requirements may vary from server to server. Some more examples:

No SSL

import email.mime.text
import smtplib

msg = email.mime.text.MIMEText('hi')

with smtplib.SMTP('smtp.gmail.com', 465) as smtp:
    smtp.ehlo()
    smtp.login('user@example.com', 'password')
    smtp.sendmail('from_user@example.com', ['to_user@example.com'], msg.as_string())

SSL/TLS from start

import email.mime.text
import smtplib

msg = email.mime.text.MIMEText('hi')

# uses SSL from start
with smtplib.SMTP_SSL('smtp.gmail.com', 465) as smtp:
    smtp.ehlo()
    smtp.login('user@example.com', 'password')
    smtp.sendmail('from_user@example.com', ['to_user@example.com'], msg.as_string())

SSL/TLS after initial connection4

import email.mime.text
import smtplib

msg = email.mime.text.MIMEText('hi')

with smtplib.SMTP('smtp.gmail.com', 465) as smtp:
    smtp.ehlo()
    smtp.starttls()
    smtp.login('user@example.com', 'password')
    smtp.sendmail('from_user@example.com', ['to_user@example.com'], msg.as_string())

NOTE:

Unfortunately, it is incapable of extracting information from your email message headers, so you'll need to write a parser, or re-enter all of the recipients.

WARNING:

If you supporting python2, SMTP object must connect within try/finally to handle closing the connection.