pythonhtmlgmailgmail-apimime-message

How do I send HTML Formatted emails, through the gmail-api for python


Using the sample code from the GMail API Example: Send Mail, and after following rules for authentication, it's simple enough to send a programmatically generated email, via a gmail account. What isn't obvious from the example is how to set that email to be HTML formatted.


The Question

How do I get HTML formatting in my gmail-api send messages, using python?

I have this...

message_body = "Hello!\nYou've just received a test message!\n\nSincerely,\n-Test Message Generator\n"

and I want it to be this...

Hello!
You've just received a test message!

Sincerely,
-Test Message Generator

Example Source Code from GMail-API

Below is a slightly modified version of the example, but still works:

import argparse
import base64
from pprint import pformat
from pprint import pprint
import httplib2
import os
from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText

from apiclient import discovery
from oauth2client import client
from oauth2client import tools
from oauth2client.file import Storage


SCOPES = 'https://mail.google.com/'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Test EMail App'


def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """

    home_dir = os.path.expanduser('~')
    credential_dir = os.path.join(home_dir, '.credentials')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir,
                                   'gmail-python-quickstart.json')

    store = Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = tools.run_flow(flow, store, flags)
        else: # Needed only for compatibility with Python 2.6
            credentials = tools.run(flow, store)
        print('Storing credentials to ' + credential_path)
    return credentials

def create_message(sender, to, cc, subject, message_text):
    """Create a message for an email.

    Args:
    sender: Email address of the sender.
    to: Email address of the receiver.
    subject: The subject of the email message.
    message_text: The text of the email message.

    Returns:
    An object containing a base64url encoded email object.
    """
    print(sender + ', ' + to + ', ' + subject + ', ' + message_text)
    message = MIMEText(message_text)
    message['to'] = to
    message['from'] = sender
    message['subject'] = subject
    message['cc'] = cc
    pprint(message)
    return {'raw': base64.urlsafe_b64encode(message.as_string())}

def send_message(service, user_id, message_in):
    """Send an email message.

    Args:
    service: Authorized Gmail API service instance.
    user_id: User's email address. The special value "me"
    can be used to indicate the authenticated user.
    message: Message to be sent.

    Returns:
    Sent Message.
    """
    pprint(message_in)
    try:
        message = (service.users().messages().send(userId=user_id, body=message_in).execute())
        pprint(message)
        print ('Message Id: %s' % message['id'])
        return message
    except errors.HttpError, error:
        print ('An error occurred: %s' % error)

def main(cli):
    """Shows basic usage of the Gmail API.

    Creates a Gmail API service object and outputs a list of label names
    of the user's Gmail account.
    """


    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('gmail', 'v1', http=http)

    email_msg = create_message(cli.addr_from, cli.addr_to, cli.addr_cc, cli.subject, cli.message)
    msg_out = service.users().messages().send(userId = 'me', body = email_msg).execute()
    pprint(msg_out)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-m', '--message',   help = 'The message to send in the email', default='<MESSAGE = unfinished>')
    parser.add_argument('-t', '--addr_to',   help = 'the list of comma separated emails to send', default='cbsd.tools@gmail.com')
    parser.add_argument('-s', '--subject',   help = 'the email subject', default='<SUBJECT = undefined>')
    parser.add_argument('-c', '--addr_cc',   help = 'email CC\'s', default='')
    parser.add_argument('-f', '--addr_from', help = 'Email address to send from', default='cbsd.tools@gmail.com')
    cli = parser.parse_args()
    pprint(dir(cli))

    main(cli)

Tried as I might, with this code, and variations on it, I could not get html formatted code, nor could I get simple escape characters to create carriage returns where they needed to be.


Here's what didn't work

Trying the following didn't work either:

  1. modifying line 69 to add additional message dictionary parameters... ie.
    • {'raw': base64.urlsafe_b64encode(message.as_string()), 'payload': {'mimeType': 'text/html'}}
    • As documented here in the GMail API Docs
    • enter image description here
  2. Adding a variety of escaped backslashes into the message text:
    • \n... ie: \\n nor \\\n and just rendered as those exact characters
    • Adding <br> </br> <br/> did not add new lines and just rendered as those exact characters
    • Adding \r did not add new lines and just rendered as that exact character

Reasons this is not a duplicate question


Solution

  • After doing a lot of digging around, I started looking in to the python side of the message handling, and noticed that a python object is actually constructing the message to be sent for base64 encoding into the gmail-api message object constructor.

    See line 63 from above: message = MIMEText(message_text)

    The one trick that finally worked for me, after all the attempts to modify the header values and payload dict (which is a member of the message object), was to set (line 63):


    The default code supplied by Google for their gmail API only tells you how to send plain text emails, but they hide how they're doing that. ala... message = MIMEText(message_text)

    I had to look up the python class email.mime.text.MIMEText object. That's where you'll see this definition of the constructor for the MIMEText object:


    Now, you won't have anymore unexpected word wrapping applied to your messages by Google, or the Python mime.text.MIMEText object


    The Fixed Code

    def create_message(sender, to, cc, subject, message_text):
        """Create a message for an email.
    
        Args:
        sender: Email address of the sender.
        to: Email address of the receiver.
        subject: The subject of the email message.
        message_text: The text of the email message.
    
        Returns:
        An object containing a base64url encoded email object.
        """
        print(sender + ', ' + to + ', ' + subject + ', ' + message_text)
        message = MIMEText(message_text,'html')
        message['to'] = to
        message['from'] = sender
        message['subject'] = subject
        message['cc'] = cc
        pprint(message)
        return {'raw': base64.urlsafe_b64encode(message.as_string())}