Sorry, unexpected error: 'module' object has no attribute 'SMTP_SSL'

Question

This is my code for my main.py file which is designed to be a simple contact form built in flask.

from flask import Flask, render_template, request
from flask_mail import Mail, Message
from forms import ContactForm


app = Flask(__name__)
app.secret_key = 'YourSuperSecreteKey'

# add mail server config
app.config['MAIL_SERVER'] = 'smtp.gmail.com'
app.config['MAIL_PORT'] = 465
app.config['MAIL_USE_SSL'] = True
app.config['MAIL_USERNAME'] = 'YourUser@NameHere'
app.config['MAIL_PASSWORD'] = 'yourMailPassword'

mail = Mail(app)

@app.route('/')
def hello():
    """Return a friendly HTTP greeting."""
    return 'Hello World!'


@app.errorhandler(404)
def page_not_found(e):
    """Return a custom 404 error."""
    return 'Sorry, Nothing at this URL.', 404


@app.errorhandler(500)
def application_error(e):
    """Return a custom 500 error."""
    return 'Sorry, unexpected error: {}'.format(e), 500

@app.route('/contact', methods=('GET', 'POST'))
def contact():
    form = ContactForm()

    if request.method == 'POST':
        if form.validate() == False:
            return 'Please fill in all fields <p><a href="/contact">Try Again!!!</a></p>'
        else:
            msg = Message("Message from your visitor" + form.name.data,
                          sender='YourUser@NameHere',
                          recipients=['yourRecieve@mail.com', 'someOther@mail.com'])
            msg.body = """
            From: %s <%s>,
            %s
            """ % (form.name.data, form.email.data, form.message.data)
            mail.send(msg)
            return "Successfully  sent message!"
    elif request.method == 'GET':
        return render_template('contact.html', form=form)

if __name__ == '__main__':
    app.run()

I get the error: Sorry, unexpected error: 'module' object has no attribute 'SMTP_SSL'

I've called my file "main.py". Everything works fine until I try and send the actual email. Is this just because I haven't populated the settings or is something else a miss?

Sorry just figured out how to see traceback on GAE:

Exception on /contact [POST]
Traceback (most recent call last):
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/main.py", line 50, in contact
    mail.send(msg)
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask_mail.py", line 491, in send
    with self.connect() as connection:
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask_mail.py", line 144, in __enter__
    self.host = self.configure_host()
  File "/base/data/home/apps/s~smart-cove-95709/1.384663697853252774/lib/flask_mail.py", line 156, in configure_host
    host = smtplib.SMTP_SSL(self.mail.server, self.mail.port)
AttributeError: 'module' object has no attribute 'SMTP_SSL'

Answer 1

You have set the MAIL_USE_SSL option to True:

app.config['MAIL_USE_SSL'] = True

which means that the Flask-Mail extension will want to use the smtplib.SMTP_SSL class, but that class isn't usually available on Google App Engine.

That class is only available if the Python ssl module is available, which is only the case if your Python was built with SSL support available. This isn't normally the case in the GAE environment.

The module is not available on Google App Engine unless you specifically enable it. Enable it in your app.yaml:

libraries:
- name: ssl
  version: latest

Do note that the socket support on GAE is experimental.

For sending email on GAE you are better off using the mail.send_mail() function however, so you can make use of the GAE infrastructure instead.