Send an email using GMail to one or more recipients.

send_email.py

"""
MIT License

Copyright (c) 2018-2020 Mark Douthwaite

Send Email Snippet
------------------

Send an email from a given account to a target set of recipients.

If you're using GMail (as the example is configured for by default), you'll need to
make sure you've set your 'sender' account to enable 'Less secure app access'. You
can do this by going to your GMail account settings > Accounts and Import, click
'Other Google Account Settings', head to 'Security', find the 'Less secure app access'
section and toggle it on. You should now be able to send emails.
"""

import os
import smtplib
from typing import List, Optional, Any
from email.message import EmailMessage


def prepare_message(
    sender: str, receivers: List[str], subject: str, content: str
) -> EmailMessage:
    """Create a new EmailMessage and prepare it to be sent."""

    message = EmailMessage()
    message.set_content(content)
    message["subject"] = subject
    message["from"] = sender
    message["to"] = ", ".join(receivers)
    return message


def send(
    sender: str,
    receivers: List[str],
    password: str = os.getenv("PASSWORD"),
    host: str = "smtp.gmail.com",
    port: int = 465,
    **kwargs: Optional[Any],
) -> None:
    """Send a message from 'sender' to provided 'receivers'."""

    with smtplib.SMTP_SSL(host, port=port) as server:
        server.login(sender, password)
        message = prepare_message(sender, receivers, **kwargs)
        server.send_message(message)


# set up your senders and receivers.
FROM: str = "you.account@gmail.com"
TO: List[str] = ["jane.smith@gmail.com", "john.appleseed@gmail.com"]

# send a simple string.
send(FROM, TO, subject="Test Email", content="Hello, world!")

# send from file
with open("newsletter.html", "r") as newsletter:
    send(FROM, TO, subject="My Newsletter", content=newsletter.read())