email.py

from flask import current_app, render_template
from flask_mail import Message
from threading import Thread
from app import mail


def create_message(recipient, subject, template, **kwargs):
    subject_prefix: str = current_app.config['NOPAQUE_MAIL_SUBJECT_PREFIX']
    msg: Message = Message(
        body=render_template(f'{template}.txt.j2', **kwargs),
        html=render_template(f'{template}.html.j2', **kwargs),
        recipients=[recipient],
        subject=f'{subject_prefix} {subject}'
    )
    return msg


def send(msg, *args, **kwargs):
    def _send(app, msg):
        with app.app_context():
            mail.send(msg)

    thread = Thread(target=_send, args=[current_app._get_current_object(), msg])
    thread.start()
    return thread