flask mail error "SMTPServerDisconnected('please run connect() first')"

Question

I am trying to send bulk emails with flask mail... here is my code

users = models.User.query.filter_by(query_email_notification=1).all()
    if users:
        # Bulk emails... keep connection open
        with app.app_context():
            with mail.connect() as conn:
                for user in users:
                    subject = "subject"
                    message = "message"
                    msg = Message(recipients=[user.email],
                                  body=message,
                                  subject=subject,
                                  sender='myemail@gmail.com')

                    conn.send(msg)

and my flask mail setup is as follows

from flask_mail import Message
app.config.update(dict(
    DEBUG = True,
    MAIL_SERVER = 'smtp.gmail.com',
    MAIL_PORT = 587,
    MAIL_USE_TLS = True,
    MAIL_USE_SSL = False,
    MAIL_USERNAME = 'myemail@gmail.com',
    MAIL_PASSWORD = 'password',
))

mail.init_app(app)

this works for a certain number of emails, but after about 100 emails I get

    raise SMTPServerDisconnected('please run connect() first')
smtplib.SMTPServerDisconnected: please run connect() first

I noticed that gmail limits the number of emails per day to 2000, but I made sure I do not hit that limit. any ideas what else I could check?

Is the MAIL_MAX_EMAILS config variable a solution? It will reconnect after a certain number of emails send...? I am looking for a reliable solution. So if sending many emails through gmail is not a good choice, what else would you recommend? thanks carl

Answer 1

Google drops the connection thinking it is a spam. Use a waiting time after each message sent successfully, something like:

time.sleep(80)

This will wait 80 seconds.