https://realpython.com/python-send-email/ as a service function

gmail_service.py

import os
import smtplib
import ssl

from email import encoders
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText


def send_mail(receiver_email, subject, body, filename=None):
    sender_email = os.environ.get("GMAIL_SENDER_EMAIL")
    password = os.environ.get("GMAIL_SENDER_PASSWORD")
    message = MIMEMultipart()
    message["FROM"] = sender_email
    message["TO"] = receiver_email
    message["SUBJECT"] = subject
    message.attach(MIMEText(body, "html"))

    if filename is not None:
        with open(filename, "rb") as attachment:
            part = MIMEBase("application", "octet-stream")
            part.set_payload(attachment.read())

        encoders.encode_base64(part)
        part.add_header(
            "Content-Disposition",
            f"attachment; filename= {filename}",
        )
        message.attach(part)

    text = message.as_string()

    context = ssl.create_default_context()
    with smtplib.SMTP_SSL("smtp.gmail.com", 465, context=context) as server:
        server.login(sender_email, password)
        server.sendmail(sender_email, receiver_email, text)