Read and Send Email with Python

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Submitted by NanoDano on Sat, 03/14/2020 - 17:44

Introduction

Python 3 has built-in libraries for IMAP, POP3, and SMTP. We will focus on learning how to send mail with SMTP and read/manage email with IMAP. We will also look at how to send an SMS text message using email.

If you need your own email hosting, check out Interserver.net hosting where you can host unlimited emails for unlimited domains as cheap as $4/month. You could also set up your own SMTP server on a VPS, but that is a hassle.

A note about Gmail

Gmail will not let you use IMAP or POP by default and you must enable the feature.

To do this, go to your Gmail settings, and choose "Enable IMAP" under the "Forwarding and POP/IMAP" tab. See: Check Gmail through other email platforms for more information.

Your username is full email address at Gmail. Both IMAP and SMTP require authentication. The server names and ports are:

  • imap.gmail.com:993 (SSL/TLS enabled)
  • smtp.gmail.com:465 (SSL/TLS enabled) Port 587 for TLS/STARTTLS

Read email with IMAP

To fetch emails, you can use poplib for POP3 or imaplib to use IMAP4. We will focus only on IMAP which give you more options.

Use IMAP4 or IMAP4_SSL class depending on whether you are using SSL. This example will use IMAP4_SSL.

  • Port 143 - Default unencrypted IMAP port
  • Port 993 - Default SSL IMAP port
imaplib.IMAP4(host='', port=IMAP4_PORT)

imaplib.IMAP4_SSL(host='', port=IMAP4_SSL_PORT, keyfile=None, certfile=None, ssl_context=None)

To keep the first example simple, this is a minimal simple example of checking an inbox:

import imaplib
# Connect to inbox
imap_server = imaplib.IMAP4_SSL(host='mail.example.com')
imap_server.login('someone@example.com', '$ecret')
imap_server.select()  # Default is `INBOX`

# Find all emails in inbox and print out the raw email data
_, message_numbers_raw = imap_server.search(None, 'ALL')
for message_number in message_numbers_raw[0].split():
    _, msg = imap_server.fetch(message_number, '(RFC822)')
    print(msg[0][1])

This next example will show how to do more common operations like:

  • Connect to IMAP server
  • List folders (mailboxes)
  • Create, rename, and delete folders (mailboxes)
  • Search emails
  • Fetch emails
  • Mark an email as read or unread
  • Move an email to a different folder
  • Delete an email
import imaplib

# Connect and login to IMAP mail server
username = 'me@example.com'
password = 'password'
mail_server = 'mail.example.com'
imap_server = imaplib.IMAP4_SSL(host=mail_server)
imap_server.login(username, password)

# List mailboxes (folders)
response_code, folders = imap_server.list()
print(response_code)  # OK
print('Available folders(mailboxes) to select:')
for folder_details_raw in folders:
    folder_details = folder_details_raw.decode().split()
    print(f'- {folder_details[-1]}')

# Create, rename, and delete mailboxes (folders)
# This format is the one my email provider interserver.net uses
# Create a mailbox
response_code, response_details = imap_server.create('INBOX.myfavorites')
print(response_code)  # `OK` on success or `NO` on failure
print(response_details)  # Create completed/Mailbox already exists
# Rename a mailbox
imap_server.rename('INBOX.myfavorites', 'INBOX.faves')
# Delete a mailbox
imap_server.delete('INBOX.faves')

# Choose the mailbox (folder) to search
# Case sensitive!
imap_server.select('INBOX')  # Default is `INBOX`

# Search for emails in the mailbox that was selected.
# First, you need to search and get the message IDs.
# Then you can fetch specific messages with the IDs.
# Search filters are explained in the RFC at:
# https://tools.ietf.org/html/rfc3501#section-6.4.4
search_criteria = 'ALL'
charset = None  # All
respose_code, message_numbers_raw = imap_server.search(charset, search_criteria)
print(f'Search response: {respose_code}')  # e.g. OK
print(f'Message numbers: {message_numbers_raw}')  # e.g. ['1 2'] A list, with string of message IDs
message_numbers = message_numbers_raw[0].split()

# Fetch full message based on the message numbers obtained from search
for message_number in message_numbers:
    response_code, message_data = imap_server.fetch(message_number, '(RFC822)')
    print(f'Fetch response for message {message_number}: {response_code}')
    print(f'Raw email data:\n{message_data[0][1]}')

    # Mark an email read/unread.
    # Other flags you can set with store() from RFC3501 include: 
    # \Seen \Answered \Flagged \Deleted \Draft \Recent
    imap_server.store(message_number, '+FLAGS', '\SEEN')  # Mark as read
    imap_server.store(message_number, '-FLAGS', '\SEEN')  # Mark as unread

    # Copy an email to a different 
    imap_server.create('INBOX.mykeepers')
    imap_server.copy(message_number, 'INBOX.mykeepers')
    # Delete an email
    imap_server.store(message_number, '+FLAGS', '\Deleted')
    # Expunge after marking emails deleted
    imap_server.expunge()


imap_server.close()
imap_server.logout()

Parse email contents

In the previous example we showed how to fetch the raw email data, but it includes the headers, the body, and everything in a single blob. That raw content is the equivalent of a .eml message. Python has an email package that will parse this raw data and provide us a useful object.

You can parse the email with email.parser. There is also a function named email.message_from_bytes() that you can use to parse directly from the raw bytes like we will have. Once you have the email.message.Message you can check various aspects like if it is multipart, content type, and get the payload.

This example will build on top of the simple inbox check example above and demonstrate how to:

  • Parse email message
    • Get to/from/cc/bcc email addresses
    • Get plain text version
    • Get html version
    • Get attachments
import imaplib
import email

# Connect to inbox
imap_server = imaplib.IMAP4_SSL(host='mail.example.com')
imap_server.login('someone@example.com', '$ecret')
imap_server.select()  # Default is `INBOX`

# Find all emails in inbox
_, message_numbers_raw = imap_server.search(None, 'ALL')
for message_number in message_numbers_raw[0].split():
    _, msg = imap_server.fetch(message_number, '(RFC822)')

    # Parse the raw email message in to a convenient object
    message = email.message_from_bytes(msg[0][1])
    print('== Email message =====')
    # print(message)  # print FULL message
    print('== Email details =====')
    print(f'From: {message["from"]}')
    print(f'To: {message["to"]}')
    print(f'Cc: {message["cc"]}')
    print(f'Bcc: {message["bcc"]}')
    print(f'Urgency (1 highest 5 lowest): {message["x-priority"]}')
    print(f'Object type: {type(message)}')
    print(f'Content type: {message.get_content_type()}')
    print(f'Content disposition: {message.get_content_disposition()}')
    print(f'Multipart?: {message.is_multipart()}')
    # If the message is multipart, it basically has multiple emails inside
    # so you must extract each "submail" separately.
    if message.is_multipart():
        print('Multipart types:')
        for part in message.walk():
            print(f'- {part.get_content_type()}')
        multipart_payload = message.get_payload()
        for sub_message in multipart_payload:
            # The actual text/HTML email contents, or attachment data
            print(f'Payload\n{sub_message.get_payload()}')
    else:  # Not a multipart message, payload is simple string
        print(f'Payload\n{message.get_payload()}')
    # You could also use `message.iter_attachments()` to get attachments only

Note that if you have an email on disk and you want to parse it directly from a file, you can use the email.parser.BytesParser like this:

from email.parser import BytesParser

with open('some_email.eml', 'rb') as email_file:
    message = BytesParser().parse(email_file)

If you want to pull attachments only from an email ignoring the body, you can use iter_attachments().

Send email with SMTP

Let's look at how to send an email using Python. First, we'll look at sending a very basic plaintext email using smtplib. Then we'll craft a multipart email message using the email.message with text, HTML, and attachments.

These examples will use an encrypted SSL SMTP server. The default port for SMTP with SSL is 587.

  • Port 25 - Default unencrypted SMTP port
  • Port 587 - Default encrypted SSL SMTP port
  • Port 465 - Non-standard port for SSL SMTP that is rarely used

Note that your from address can be very important. Some firewalls and email servers will prevent your email from going through if you use a domain name that does not match the sending host, so you can't pretend to be @google.com.

Send plaintext email

This first example will show the simplest example of sending a mail with SMTP. The email will be crafted by hand, with the headers first, followed by a blank line, followed by the plain-text body.

from smtplib import SMTP_SSL, SMTP_SSL_PORT

SMTP_HOST = 'mail.example.com'
SMTP_USER = 'someone@example.com'
SMTP_PASS = 'Secret!'

# Craft the email by hand
from_email = 'My name <someone@example.com>'  # or simply the email address
to_emails = ['nanodano@devdungeon.com', 'admin@devdungeon.com']
body = "Hello, world!"
headers = f"From: {from_email}\r\n"
headers += f"To: {', '.join(to_emails)}\r\n" 
headers += f"Subject: Hello\r\n"
email_message = headers + "\r\n" + body  # Blank line needed between headers and body

# Connect, authenticate, and send mail
smtp_server = SMTP_SSL(SMTP_HOST, port=SMTP_SSL_PORT)
smtp_server.set_debuglevel(1)  # Show SMTP server interactions
smtp_server.login(SMTP_USER, SMTP_PASS)
smtp_server.sendmail(from_email, to_emails, email_message)

# Disconnect
smtp_server.quit()

Instead of creating the email as a big raw string, you can use the email.message.EmailMessage class to manage en email easier. This example will show how to

  • Create an email message object
  • Set to and from addresses
  • Set the subject
  • Add the urgent flag
  • Set body of email
from smtplib import SMTP_SSL, SMTP_SSL_PORT
from email.message import EmailMessage

# Craft the email using email.message.EmailMessage
from_email = 'My name <someone@examples.com>'  # or simply the email address
to_emails = ['nanodano@devdungeon.com', 'admin@devdungeon.com']
email_message = EmailMessage()
email_message.add_header('To', ', '.join(to_emails))
email_message.add_header('From', from_email)
email_message.add_header('Subject', 'Hello!')
email_message.add_header('X-Priority', '1')  # Urgency, 1 highest, 5 lowest
email_message.set_content('Hello, world!')

# Connect, authenticate, and send mail
smtp_server = SMTP_SSL('mail.example.com', port=SMTP_SSL_PORT)
smtp_server.set_debuglevel(1)  # Show SMTP server interactions
smtp_server.login('user@example.com', 'pass')
smtp_server.sendmail(from_email, to_emails, email_message.as_bytes())

# Disconnect
smtp_server.quit()

Send multipart HTML email with attachments

To create a multipart email that contains text and HTML versions along with attachments, you can use the email.mime.multipart.MIMEMultipart class.

email.mime.multipart.MIMEMultipart(_subtype='mixed', boundary=None, _subparts=None, *, policy=compat32, **_params)

To use a MIMEMultipart, first create the object just like a normal email.message.EmailMessage. Instead of setting the content though, we will attach() all of the parts, including the text version, html version, and any attachments.

This example will show how to create a multipart MIME email that has

  • Plain-text version of email
  • HTML version of email
  • Attachments
from smtplib import SMTP_SSL, SMTP_SSL_PORT
from email.mime.multipart import MIMEMultipart, MIMEBase
from email.mime.text import MIMEText
from email.encoders import encode_base64

from_email = 'My name <someone@example.com>'  # or simply the email address
to_emails = ['nanodano@devdungeon.com', 'admin@devdungeon.com']

# Create multipart MIME email
email_message = MIMEMultipart()
email_message.add_header('To', ', '.join(to_emails))
email_message.add_header('From', from_email)
email_message.add_header('Subject', 'Hello!')
email_message.add_header('X-Priority', '1')  # Urgent/High priority

# Create text and HTML bodies for email
text_part = MIMEText('Hello world plain text!', 'plain')
html_part = MIMEText('<html><body><h1>HTML!</h1></body></html>', 'html')

# Create file attachment
attachment = MIMEBase("application", "octet-stream")
attachment.set_payload(b'\xDE\xAD\xBE\xEF')  # Raw attachment data
encode_base64(attachment)
attachment.add_header("Content-Disposition", "attachment; filename=myfile.dat")

# Attach all the parts to the Multipart MIME email
email_message.attach(text_part)
email_message.attach(html_part)
email_message.attach(attachment)

# Connect, authenticate, and send mail
smtp_server = SMTP_SSL('mail.example.com', port=SMTP_SSL_PORT)
smtp_server.set_debuglevel(1)  # Show SMTP server interactions
smtp_server.login('user@email.com', 'password')
smtp_server.sendmail(from_email, to_emails, email_message.as_bytes())

# Disconnect
smtp_server.quit()

Email templates with Jinja2

If you want to create a text or HTML template for re-use, I recommend Jinja2 templates.

Here is a very basic example of how a Jinja2 template can be used. Refer to the Jinja2 documentation for more details.

# pip install jinja2
from jinja2 import Template

template = Template('Hello, {{ name }}!')
print(template.render({'name': 'My Name'}))

Send a text message (SMS/MMS) via email

Most cell phone service providers also offer an email gateway that lets you email an address and it will send an SMS/MMS to the cell phone.

For a detailed list of SMS email gateways listed by provider, check out SMS gateways on Wikipedia.

For example, to text the number 888-123-4567 on AT&T, I could send an email to:

8881234567@txt.att.net

Conclusion

After reading this guide, you should understand how to use Python to read mail with IMAP and how to send mail using SMTP with plain-text or HTML emails along with attachments.

References

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