Enviar um e-mail através do gmail & python

Modifiquei isto da seguinte forma para trabalhar com o Python3, inspirado em a API do Python Gmail 'não é serializável pelo JSON'

import httplib2
import os
import oauth2client
from oauth2client import client, tools
import base64
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from apiclient import errors, discovery

SCOPES = 'https://www.googleapis.com/auth/gmail.send'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Gmail API Python Send Email'

def get_credentials():
    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-email-send.json')
    store = oauth2client.file.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
        credentials = tools.run_flow(flow, store)
        print('Storing credentials to ' + credential_path)
    return credentials

def SendMessage(sender, to, subject, msgHtml, msgPlain):
    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('gmail', 'v1', http=http)
    message1 = CreateMessage(sender, to, subject, msgHtml, msgPlain)
    SendMessageInternal(service, "me", message1)

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

def CreateMessage(sender, to, subject, msgHtml, msgPlain):
    msg = MIMEMultipart('alternative')
    msg['Subject'] = subject
    msg['From'] = sender
    msg['To'] = to
    msg.attach(MIMEText(msgPlain, 'plain'))
    msg.attach(MIMEText(msgHtml, 'html'))
    raw = base64.urlsafe_b64encode(msg.as_bytes())
    raw = raw.decode()
    body = {'raw': raw}
    return body

def main():
    to = "[email protected]"
    sender = "[email protected]"
    subject = "subject"
    msgHtml = "Hi<br/>Html Email"
    msgPlain = "Hi\nPlain Email"
    SendMessage(sender, to, subject, msgHtml, msgPlain)

if __name__ == '__main__':
    main()

Aqui está o código Python 3.6 (e explicações) necessário para enviar um e-mail sem (ou com) um anexo.

(para enviar com anexo apenas descomentar as 2 linhas abaixo ## without attachment e comentar as 2 linhas abaixo ## with attachment)

Todo o crédito (e up-vote) a apadana

import httplib2
import os
import oauth2client
from oauth2client import client, tools
import base64
from email import encoders

#needed for attachment
import smtplib  
import mimetypes
from email import encoders
from email.message import Message
from email.mime.audio import MIMEAudio
from email.mime.base import MIMEBase
from email.mime.image import MIMEImage
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.application import MIMEApplication
#List of all mimetype per extension: http://help.dottoro.com/lapuadlp.php  or http://mime.ritey.com/

from apiclient import errors, discovery  #needed for gmail service




## About credentials
# There are 2 types of "credentials": 
#     the one created and downloaded from https://console.developers.google.com/apis/ (let's call it the client_id) 
#     the one that will be created from the downloaded client_id (let's call it credentials, it will be store in C:\Users\user\.credentials)


        #Getting the CLIENT_ID 
            # 1) enable the api you need on https://console.developers.google.com/apis/
            # 2) download the .json file (this is the CLIENT_ID)
            # 3) save the CLIENT_ID in same folder as your script.py 
            # 4) update the CLIENT_SECRET_FILE (in the code below) with the CLIENT_ID filename


        #Optional
        # If you don't change the permission ("scope"): 
            #the CLIENT_ID could be deleted after creating the credential (after the first run)

        # If you need to change the scope:
            # you will need the CLIENT_ID each time to create a new credential that contains the new scope.
            # Set a new credentials_path for the new credential (because it's another file)
def get_credentials():
    # If needed create folder for credential
    home_dir = os.path.expanduser('~') #>> C:\Users\Me
    credential_dir = os.path.join(home_dir, '.credentials') # >>C:\Users\Me\.credentials   (it's a folder)
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)  #create folder if doesnt exist
    credential_path = os.path.join(credential_dir, 'cred send mail.json')

    #Store the credential
    store = oauth2client.file.Storage(credential_path)
    credentials = store.get()

    if not credentials or credentials.invalid:
        CLIENT_SECRET_FILE = 'client_id to send Gmail.json'
        APPLICATION_NAME = 'Gmail API Python Send Email'
        #The scope URL for read/write access to a user's calendar data  

        SCOPES = 'https://www.googleapis.com/auth/gmail.send'

        # Create a flow object. (it assists with OAuth 2.0 steps to get user authorization + credentials)
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME

        credentials = tools.run_flow(flow, store)

    return credentials




## Get creds, prepare message and send it
def create_message_and_send(sender, to, subject,  message_text_plain, message_text_html, attached_file):
    credentials = get_credentials()

    # Create an httplib2.Http object to handle our HTTP requests, and authorize it using credentials.authorize()
    http = httplib2.Http()

    # http is the authorized httplib2.Http() 
    http = credentials.authorize(http)        #or: http = credentials.authorize(httplib2.Http())

    service = discovery.build('gmail', 'v1', http=http)

    ## without attachment
    message_without_attachment = create_message_without_attachment(sender, to, subject, message_text_html, message_text_plain)
    send_Message_without_attachement(service, "me", message_without_attachment, message_text_plain)


    ## with attachment
    # message_with_attachment = create_Message_with_attachment(sender, to, subject, message_text_plain, message_text_html, attached_file)
    # send_Message_with_attachement(service, "me", message_with_attachment, message_text_plain,attached_file)

def create_message_without_attachment (sender, to, subject, message_text_html, message_text_plain):
    #Create message container
    message = MIMEMultipart('alternative') # needed for both plain & HTML (the MIME type is multipart/alternative)
    message['Subject'] = subject
    message['From'] = sender
    message['To'] = to

    #Create the body of the message (a plain-text and an HTML version)
    message.attach(MIMEText(message_text_plain, 'plain'))
    message.attach(MIMEText(message_text_html, 'html'))

    raw_message_no_attachment = base64.urlsafe_b64encode(message.as_bytes())
    raw_message_no_attachment = raw_message_no_attachment.decode()
    body  = {'raw': raw_message_no_attachment}
    return body



def create_Message_with_attachment(sender, to, subject, message_text_plain, message_text_html, attached_file):
    """Create a message for an email.

    message_text: The text of the email message.
    attached_file: The path to the file to be attached.

    Returns:
    An object containing a base64url encoded email object.
    """

    ##An email is composed of 3 part :
        #part 1: create the message container using a dictionary { to, from, subject }
        #part 2: attach the message_text with .attach() (could be plain and/or html)
        #part 3(optional): an attachment added with .attach() 

    ## Part 1
    message = MIMEMultipart() #when alternative: no attach, but only plain_text
    message['to'] = to
    message['from'] = sender
    message['subject'] = subject

    ## Part 2   (the message_text)
    # The order count: the first (html) will be use for email, the second will be attached (unless you comment it)
    message.attach(MIMEText(message_text_html, 'html'))
    message.attach(MIMEText(message_text_plain, 'plain'))

    ## Part 3 (attachement) 
    # # to attach a text file you containing "test" you would do:
    # # message.attach(MIMEText("test", 'plain'))

    #-----About MimeTypes:
    # It tells gmail which application it should use to read the attachement (it acts like an extension for windows).
    # If you dont provide it, you just wont be able to read the attachement (eg. a text) within gmail. You'll have to download it to read it (windows will know how to read it with it's extension). 

    #-----3.1 get MimeType of attachment
        #option 1: if you want to attach the same file just specify it’s mime types

        #option 2: if you want to attach any file use mimetypes.guess_type(attached_file) 

    my_mimetype, encoding = mimetypes.guess_type(attached_file)

    # If the extension is not recognized it will return: (None, None)
    # If it's an .mp3, it will return: (audio/mp3, None) (None is for the encoding)
    #for unrecognized extension it set my_mimetypes to  'application/octet-stream' (so it won't return None again). 
    if my_mimetype is None or encoding is not None:
        my_mimetype = 'application/octet-stream' 


    main_type, sub_type = my_mimetype.split('/', 1)# split only at the first '/'
    # if my_mimetype is audio/mp3: main_type=audio sub_type=mp3

    #-----3.2  creating the attachement
        #you don't really "attach" the file but you attach a variable that contains the "binary content" of the file you want to attach

        #option 1: use MIMEBase for all my_mimetype (cf below)  - this is the easiest one to understand
        #option 2: use the specific MIME (ex for .mp3 = MIMEAudio)   - it's a shorcut version of MIMEBase

    #this part is used to tell how the file should be read and stored (r, or rb, etc.)
    if main_type == 'text':
        print("text")
        temp = open(attached_file, 'r')  # 'rb' will send this error: 'bytes' object has no attribute 'encode'
        attachement = MIMEText(temp.read(), _subtype=sub_type)
        temp.close()

    elif main_type == 'image':
        print("image")
        temp = open(attached_file, 'rb')
        attachement = MIMEImage(temp.read(), _subtype=sub_type)
        temp.close()

    elif main_type == 'audio':
        print("audio")
        temp = open(attached_file, 'rb')
        attachement = MIMEAudio(temp.read(), _subtype=sub_type)
        temp.close()            

    elif main_type == 'application' and sub_type == 'pdf':   
        temp = open(attached_file, 'rb')
        attachement = MIMEApplication(temp.read(), _subtype=sub_type)
        temp.close()

    else:                              
        attachement = MIMEBase(main_type, sub_type)
        temp = open(attached_file, 'rb')
        attachement.set_payload(temp.read())
        temp.close()

    #-----3.3 encode the attachment, add a header and attach it to the message
    encoders.encode_base64(attachement)  #https://docs.python.org/3/library/email-examples.html
    filename = os.path.basename(attached_file)
    attachement.add_header('Content-Disposition', 'attachment', filename=filename) # name preview in email
    message.attach(attachement) 


    ## Part 4 encode the message (the message should be in bytes)
    message_as_bytes = message.as_bytes() # the message should converted from string to bytes.
    message_as_base64 = base64.urlsafe_b64encode(message_as_bytes) #encode in base64 (printable letters coding)
    raw = message_as_base64.decode()  # need to JSON serializable (no idea what does it means)
    return {'raw': raw} 



def send_Message_without_attachement(service, user_id, body, message_text_plain):
    try:
        message_sent = (service.users().messages().send(userId=user_id, body=body).execute())
        message_id = message_sent['id']
        # print(attached_file)
        print (f'Message sent (without attachment) \n\n Message Id: {message_id}\n\n Message:\n\n {message_text_plain}')
        # return body
    except errors.HttpError as error:
        print (f'An error occurred: {error}')




def send_Message_with_attachement(service, user_id, message_with_attachment, message_text_plain, attached_file):
    """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.
    """
    try:
        message_sent = (service.users().messages().send(userId=user_id, body=message_with_attachment).execute())
        message_id = message_sent['id']
        # print(attached_file)

        # return message_sent
    except errors.HttpError as error:
        print (f'An error occurred: {error}')


def main():
    to = "[email protected]"
    sender = "[email protected]"
    subject = "subject test1"
    message_text_html  = r'Hi<br/>Html <b>hello</b>'
    message_text_plain = "Hi\nPlain Email"
    attached_file = r'C:\Users\Me\Desktop\audio.m4a'
    create_message_and_send(sender, to, subject, message_text_plain, message_text_html, attached_file)


if __name__ == '__main__':
        main()

print (f'An error occurred: {error}')

A

print ('An error occurred: {error}')

Veja também a primeira parte da resposta de @apandana para obter o seu client_secret.ficheiro json. Isso foi mais claro para mim.

Para os utilizadores do jupyter-notebook, depois de seguir as instruções de @apadana, se receber mensagens de erro críptico, certifique-se de copiar o código para o seu próprio ficheiro python e executá-lo usando

%run [filename].py

Faça a última alteração: o erro da API do Gmail a partir da amostra de código - um objecto semelhante a bytes é necessário, não "str'

Substituir

return {'raw': base64.urlsafe_b64encode(message.as_string())}

Com:

return {'raw': base64.urlsafe_b64encode(message.as_string().encode()).decode()}

Notas finais: lembrem-se que há duas instâncias da Base 64 codificam a coisa...

Utilizar

return {'raw': base64.urlsafe_b64encode(msg.as_string().encode()).decode()}

Em método CreateMessageHtml

E

return {'raw': base64.urlsafe_b64encode(message.as_string().encode()).decode()}

Em método, criar uma mudança de atitude

A razão pela qual você tem que fazer isso é porque a mensagem tem o nome variável 'msg' em CreateMessageHtml, mas o nome 'mensagem' em createMessageWithAttachment. Porque questao. É por isso.