2018-02-06T15:11:28Z

The Flask Mega-Tutorial Part X: Email Support

This is the tenth installment of the Flask Mega-Tutorial series, in which I'm going to tell you how your application can send emails to your users, and how to build a password recovery feature on top of the email support.

For your reference, below is a list of the articles in this series.

The application is doing pretty well on the database front now, so in this chapter I want to depart from that topic and add another important piece that most web applications need, which is the sending of emails.

Why does an application need to email its users? There are many reasons, but one common one is to solve authentication related problems. In this chapter I'm going to add a password reset feature for users that forget their password. When a user requests a password reset, the application will send an email with a specially crafted link. The user then needs to click that link to have access to a form in which to set a new password.

The GitHub links for this chapter are: Browse, Zip, Diff.

Introduction to Flask-Mail

As far as the actual sending of emails, Flask has a popular extension called Flask-Mail that can make the task very easy. As always, this extension is installed with pip:

(venv) $ pip install flask-mail

The password reset links will have a secure token in them. To generate these tokens, I'm going to use JSON Web Tokens, which also have a popular Python package:

(venv) $ pip install pyjwt

The Flask-Mail extension is configured from the app.config object. Remember when in Chapter 7 I added the email configuration for sending yourself an email whenever an error occurred in production? I did not tell you this then, but my choice of configuration variables was modeled after Flask-Mail's requirements, so there isn't really any additional work that is needed, the configuration variables are already in the application.

Like most Flask extensions, you need to create an instance right after the Flask application is created. In this case this is an object of class Mail:

app/__init__.py: Flask-Mail instance.

# ...
from flask_mail import Mail

app = Flask(__name__)
# ...
mail = Mail(app)

If you are planning to test sending of emails you have the same options I mentioned in Chapter 7. If you want to use an emulated email server, Python provides one that is very handy that you can start in a second terminal with the following command:

(venv) $ python -m smtpd -n -c DebuggingServer localhost:8025

To configure for this server you will need to set two environment variables:

(venv) $ export MAIL_SERVER=localhost
(venv) $ export MAIL_PORT=8025

If you prefer to have emails sent for real, you need to use a real email server. If you have one, then you just need to set the MAIL_SERVER, MAIL_PORT, MAIL_USE_TLS, MAIL_USERNAME and MAIL_PASSWORD environment variables for it. If you want a quick solution, you can use a Gmail account to send email, with the following settings:

(venv) $ export MAIL_SERVER=smtp.googlemail.com
(venv) $ export MAIL_PORT=587
(venv) $ export MAIL_USE_TLS=1
(venv) $ export MAIL_USERNAME=<your-gmail-username>
(venv) $ export MAIL_PASSWORD=<your-gmail-password>

If you are using Microsoft Windows, you need to replace export with set in each of the export statements above.

Remember that the security features in your Gmail account may prevent the application from sending emails through it unless you explicitly allow "less secure apps" access to your Gmail account. You can read about this here, and if you are concerned about the security of your account, you can create a secondary account that you configure just for testing emails, or you can enable less secure apps only temporarily to run your tests and then revert back to the more secure default.

If you'd like to use a real email server, but don't want to complicate yourself with the Gmail configuration, SendGrid is a good option that gives you 100 emails per day using a free account.

Flask-Mail Usage

To learn how Flask-Mail works, I'll show you how to send an email from a Python shell. So fire up Python with flask shell, and then run the following commands:

>>> from flask_mail import Message
>>> from app import mail
>>> msg = Message('test subject', sender=app.config['ADMINS'][0],
... recipients=['your-email@example.com'])
>>> msg.body = 'text body'
>>> msg.html = '<h1>HTML body</h1>'
>>> mail.send(msg)

The snippet of code above will send an email to a list of email addresses that you put in the recipients argument. I put the sender as the first configured admin (I've added the ADMINS configuration variable in Chapter 7). The email will have plain text and HTML versions, so depending on how your email client is configured you may see one or the other.

So as you see, this is pretty simple. Now let's integrate emails into the application.

A Simple Email Framework

I will begin by writing a helper function that sends an email, which is basically a generic version of the shell exercise from the previous section. I will put this function in a new module called app/email.py:

app/email.py: Email sending wrapper function.

from flask_mail import Message
from app import mail

def send_email(subject, sender, recipients, text_body, html_body):
    msg = Message(subject, sender=sender, recipients=recipients)
    msg.body = text_body
    msg.html = html_body
    mail.send(msg)

Flask-Mail supports some features that I'm not utilizing here such as Cc and Bcc lists. Be sure to check the Flask-Mail Documentation if you are interested in those options.

Requesting a Password Reset

As I mentioned above, I want users to have the option to request their password to be reset. For this purpose I'm going to add a link in the login page:

app/templates/login.html: Password reset link in login form.

    <p>
        Forgot Your Password?
        <a href="{{ url_for('reset_password_request') }}">Click to Reset It</a>
    </p>

When the user clicks the link, a new web form will appear that requests the user's email address as a way to initiate the password reset process. Here is the form class:

app/forms.py: Reset password request form.

class ResetPasswordRequestForm(FlaskForm):
    email = StringField('Email', validators=[DataRequired(), Email()])
    submit = SubmitField('Request Password Reset')

And here is the corresponding HTML template:

app/templates/reset_password_request.html: Reset password request template.

{% extends "base.html" %}

{% block content %}
    <h1>Reset Password</h1>
    <form action="" method="post">
        {{ form.hidden_tag() }}
        <p>
            {{ form.email.label }}<br>
            {{ form.email(size=64) }}<br>
            {% for error in form.email.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>
    </form>
{% endblock %}

I also need a view function to handle this form:

app/routes.py: Reset password request view function.

from app.forms import ResetPasswordRequestForm
from app.email import send_password_reset_email

@app.route('/reset_password_request', methods=['GET', 'POST'])
def reset_password_request():
    if current_user.is_authenticated:
        return redirect(url_for('index'))
    form = ResetPasswordRequestForm()
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()
        if user:
            send_password_reset_email(user)
        flash('Check your email for the instructions to reset your password')
        return redirect(url_for('login'))
    return render_template('reset_password_request.html',
                           title='Reset Password', form=form)

This view function is fairly similar to others that process a form. I start by making sure the user is not logged in. If the user is logged in, then there is no point in using the password reset functionality, so I redirect to the index page.

When the form is submitted and valid, I look up the user by the email provided by the user in the form. If I find the user, I send a password reset email. The send_password_reset_email() helper function performs this task. I will show you this function below.

After the email is sent, I flash a message directing the user to look for the email for further instructions, and then redirect back to the login page. You may notice that the flashed message is displayed even if the email provided by the user is unknown. This is so that clients cannot use this form to figure out if a given user is a member or not.

Password Reset Tokens

Before I implement the send_password_reset_email() function, I need to have a way to generate a password request link. This is going to be the link that is sent to the user via email. When the link is clicked, a page where a new password can be set is presented to the user. The tricky part of this plan is to make sure that only valid reset links can be used to reset an account's password.

The links are going to be provisioned with a token, and this token will be validated before allowing the password change, as proof that the user that requested the email has access to the email address on the account. A very popular token standard for this type of process is the JSON Web Token, or JWT. The nice thing about JWTs is that they are self contained. You can send a token to a user in an email, and when the user clicks the link that feeds the token back into the application, it can be verified on its own.

How do JWTs work? Nothing better than a quick Python shell session to understand them:

>>> import jwt
>>> token = jwt.encode({'a': 'b'}, 'my-secret', algorithm='HS256')
>>> token
'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhIjoiYiJ9.dvOo58OBDHiuSHD4uW88nfJik_sfUHq1mDi4G0'
>>> jwt.decode(token, 'my-secret', algorithms=['HS256'])
{'a': 'b'}

The {'a': 'b'} dictionary is an example payload that is going to be written into the token. To make the token secure, a secret key needs to be provided to be used in creating a cryptographic signature. For this example I have used the string 'my-secret', but with the application I'm going to use the SECRET_KEY from the configuration. The algorithm argument specifies how the token is to be generated. The HS256 algorithm is the most widely used.

As you can see the resulting token is a long sequence of characters. But do not think that this is an encrypted token. The contents of the token, including the payload, can be decoded easily by anyone (don't believe me? Copy the above token and then enter it in the JWT debugger to see its contents). What makes the token secure is that the payload is signed. If somebody tried to forge or tamper with the payload in a token, then the signature would be invalidated, and to generate a new signature the secret key is needed. When a token is verified, the contents of the payload are decoded and returned back to the caller. If the token's signature was validated, then the payload can be trusted as authentic.

The payload that I'm going to use for the password reset tokens is going to have the format {'reset_password': user_id, 'exp': token_expiration}. The exp field is standard for JWTs and if present it indicates an expiration time for the token. If a token has a valid signature, but it is past its expiration timestamp, then it will also be considered invalid. For the password reset feature, I'm going to give these tokens 10 minutes of life.

When the user clicks on the emailed link, the token is going to be sent back to the application as part of the URL, and the first thing the view function that handles this URL will do is to verify it. If the signature is valid, then the user can be identified by the ID stored in the payload. Once the user's identity is known, the application can ask for a new password and set it on the user's account.

Since these tokens belong to users, I'm going to write the token generation and verification functions as methods in the User model:

app/models.py: Reset password token methods.

from time import time
import jwt
from app import app

class User(UserMixin, db.Model):
    # ...

    def get_reset_password_token(self, expires_in=600):
        return jwt.encode(
            {'reset_password': self.id, 'exp': time() + expires_in},
            app.config['SECRET_KEY'], algorithm='HS256')

    @staticmethod
    def verify_reset_password_token(token):
        try:
            id = jwt.decode(token, app.config['SECRET_KEY'],
                            algorithms=['HS256'])['reset_password']
        except:
            return
        return User.query.get(id)

The get_reset_password_token() function returns a JWT token as a string, which is generated directly by the jwt.encode() function.

The verify_reset_password_token() is a static method, which means that it can be invoked directly from the class. A static method is similar to a class method, with the only difference that static methods do not receive the class as a first argument. This method takes a token and attempts to decode it by invoking PyJWT's jwt.decode() function. If the token cannot be validated or is expired, an exception will be raised, and in that case I catch it to prevent the error, and then return None to the caller. If the token is valid, then the value of the reset_password key from the token's payload is the ID of the user, so I can load the user and return it.

Sending a Password Reset Email

The send_password_reset_email() function relies on the send_email() function I wrote above to generate the password reset emails.

app/email.py: Send password reset email function.

from flask import render_template
from app import app

# ...

def send_password_reset_email(user):
    token = user.get_reset_password_token()
    send_email('[Microblog] Reset Your Password',
               sender=app.config['ADMINS'][0],
               recipients=[user.email],
               text_body=render_template('email/reset_password.txt',
                                         user=user, token=token),
               html_body=render_template('email/reset_password.html',
                                         user=user, token=token))

The interesting part in this function is that the text and HTML content for the emails is generated from templates using the familiar render_template() function. The templates receive the user and the token as arguments, so that a personalized email message can be generated. Here is the text template for the reset password email:

app/templates/email/reset_password.txt: Text for password reset email.

Dear {{ user.username }},

To reset your password click on the following link:

{{ url_for('reset_password', token=token, _external=True) }}

If you have not requested a password reset simply ignore this message.

Sincerely,

The Microblog Team

And here is the nicer HTML version of the same email:

app/templates/email/reset_password.html: HTML for password reset email.

<p>Dear {{ user.username }},</p>
<p>
    To reset your password
    <a href="{{ url_for('reset_password', token=token, _external=True) }}">
        click here
    </a>.
</p>
<p>Alternatively, you can paste the following link in your browser's address bar:</p>
t<p>{{ url_for('reset_password', token=token, _external=True) }}</p>
<p>If you have not requested a password reset simply ignore this message.</p>
<p>Sincerely,</p>
<p>The Microblog Team</p>

The reset_password route that is referenced in the url_for() call in these two email templates does not exist yet, this will be added in the next section. The _external=True argument that I included in the url_for() calls in both templates is also new. The URLs that are generated by url_for() by default are relative URLs that only include the path portion of the URL. This is normally sufficient for links that are generated in web pages, because the web browser completes the URL by taking the missing parts from the URL in the address bar. When sending a URL by email however, that context does not exist, so fully qualified URLs need to be used. When _external=True is passed as an argument, complete URLs are generated, so the previous example would return http://localhost:5000/user/susan, or the appropriate URL when the application is deployed on a domain name.

Resetting a User Password

When the user clicks on the email link, a second route associated with this feature is triggered. Here is the password request view function:

app/routes.py: Password reset view function.

from app.forms import ResetPasswordForm

@app.route('/reset_password/<token>', methods=['GET', 'POST'])
def reset_password(token):
    if current_user.is_authenticated:
        return redirect(url_for('index'))
    user = User.verify_reset_password_token(token)
    if not user:
        return redirect(url_for('index'))
    form = ResetPasswordForm()
    if form.validate_on_submit():
        user.set_password(form.password.data)
        db.session.commit()
        flash('Your password has been reset.')
        return redirect(url_for('login'))
    return render_template('reset_password.html', form=form)

In this view function I first make sure the user is not logged in, and then I determine who the user is by invoking the token verification method in the User class. This method returns the user if the token is valid, or None if not. If the token is invalid I redirect to the home page.

If the token is valid, then I present the user with a second form, in which the new password is requested. This form is processed in a way similar to previous forms, and as a result of a valid form submission, I invoke the set_password() method of User to change the password, and then redirect to the login page, where the user can now login.

Here is the ResetPasswordForm class:

app/forms.py: Password reset form.

class ResetPasswordForm(FlaskForm):
    password = PasswordField('Password', validators=[DataRequired()])
    password2 = PasswordField(
        'Repeat Password', validators=[DataRequired(), EqualTo('password')])
    submit = SubmitField('Request Password Reset')

And here is the corresponding HTML template:

app/templates/reset_password.html: Password reset form template.

{% extends "base.html" %}

{% block content %}
    <h1>Reset Your Password</h1>
    <form action="" method="post">
        {{ form.hidden_tag() }}
        <p>
            {{ form.password.label }}<br>
            {{ form.password(size=32) }}<br>
            {% for error in form.password.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.password2.label }}<br>
            {{ form.password2(size=32) }}<br>
            {% for error in form.password2.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>
    </form>
{% endblock %}

The password reset feature is now complete, so make sure you try it.

Asynchronous Emails

If you are using the simulated email server that Python provides you may not have noticed this, but sending an email slows the application down considerably. All the interactions that need to happen when sending an email make the task slow, it usually takes a few seconds to get an email out, and maybe more if the email server of the addressee is slow, or if there are multiple addressees.

What I really want is for the send_email() function to be asynchronous. What does that mean? It means that when this function is called, the task of sending the email is scheduled to happen in the background, freeing the send_email() to return immediately so that the application can continue running concurrently with the email being sent.

Python has support for running asynchronous tasks, actually in more than one way. The threading and multiprocessing modules can both do this. Starting a background thread for email being sent is much less resource intensive than starting a brand new process, so I'm going to go with that approach:

app/email.py: Send emails asynchronously.

from threading import Thread
# ...

def send_async_email(app, msg):
    with app.app_context():
        mail.send(msg)


def send_email(subject, sender, recipients, text_body, html_body):
    msg = Message(subject, sender=sender, recipients=recipients)
    msg.body = text_body
    msg.html = html_body
    Thread(target=send_async_email, args=(app, msg)).start()

The send_async_email function now runs in a background thread, invoked via the Thread class in the last line of send_email(). With this change, the sending of the email will run in the thread, and when the process completes the thread will end and clean itself up. If you have configured a real email server, you will definitely notice a speed improvement when you press the submit button on the password reset request form.

You probably expected that only the msg argument would be sent to the thread, but as you can see in the code, I'm also sending the application instance. When working with threads there is an important design aspect of Flask that needs to be kept in mind. Flask uses contexts to avoid having to pass arguments across functions. I'm not going to go into a lot of detail on this, but know that there are two types of contexts, the application context and the request context. In most cases, these contexts are automatically managed by the framework, but when the application starts custom threads, contexts for those threads may need to be manually created.

There are many extensions that require an application context to be in place to work, because that allows them to find the Flask application instance without it being passed as an argument. The reason many extensions need to know the application instance is because they have their configuration stored in the app.config object. This is exactly the situation with Flask-Mail. The mail.send() method needs to access the configuration values for the email server, and that can only be done by knowing what the application is. The application context that is created with the with app.app_context() call makes the application instance accessible via the current_app variable from Flask.

304 comments

  • #126 Roger said 2019-03-06T18:08:53Z

    Hi Miguel,

    Why is the way with the application wide security key safe? Wouldn't it be better generating a secure random token and associate it to the user (in addition to the expiration check).

    Thanks, Roger

  • #127 Miguel Grinberg said 2019-03-07T09:58:47Z

    @Roger: the SECRET_KEY has to be kept safe. If this key is compromised you have much bigger problems. But in any case, the main benefit of this solution is that it requires no storage. If you want to associate data with the user in the database, then you don't need any of this, just generate a random token using Python's secrets module and store it in the database along with the expiration time. Both solutions are good, in my opinion.

  • #128 John Palmer said 2019-03-17T23:21:00Z

    Hello Miguel,

    Would it be reasonable to change the SECRET_KEY environment variable on a regular schedule, like other keys?

    John Palmer.

  • #129 Miguel Grinberg said 2019-03-18T08:32:17Z

    @John: Yes, you can rotate your secret key on a regular schedule, but note that when you change it all your user sessions will become invalid and your users will need to login again. If you are also using this key to sign tokens, same thing, all those existing tokens will become immediately invalid. Flask unfortunately does not have a secret key upgrade mechanism that is seamless.

  • #130 Joseph DeWitt said 2019-03-27T21:20:21Z

    Hi Miguel,

    Thank you so much for writing this tutorial. After graduating school I was worried how well I'd learn new things on my own, but now I know that I can learn so so much more thanks to work like yours.

    Something I'd just like to note here, I was having many issues with getting these emails to work, getting all kinds of errors from smtplib as I tried tweaking my configuration, until I figured out that it was because I was using the development environment. I think a feature like this should be able to be tested in the development environment, so my fix was this: in init.py, I took lines 20-31, and move them above the line if not app.debug:. This way the app's SMTP_Handler is properly instantiated and configured while in the development environment, but the logger is not set up. Granted, I'm still very new to flask, I'm not sure how exactly this works because I don't see where mail_handler, which is the only place that takes the MAIL environment variables, get used.

    Could you tell me a little about how the configuration gets passed to the mail module used in email.py?

    Thanks, Joe

  • #131 Miguel Grinberg said 2019-03-28T10:07:38Z

    @Joseph: you can run in a development environment and yet have debug set to False. If you want to test emails going out on error in your environment, just run the app with debug=False.

  • #132 Darien Schettler said 2019-05-08T16:23:16Z

    I was just wondering if there is a way to have the link that we send by email to be usable only once.

    I was able to access the email multiple times and change the password multiple times.

    I'm sure this does not pose much of a concern with a 10 minute expiry, however, I am curious how/if it can be done?

    Thanks! These tutorials are great!

  • #133 Miguel Grinberg said 2019-05-08T17:25:36Z

    @Darien: there are a few ways to do it. You can save used tokens in a database table, and then make sure the token is not there before you allow the user to change the password, for example.

  • #134 Maruf said 2019-05-08T22:59:46Z

    Hi,

    I configured the app to log in the fake server that is used for debugging. but I am getting a connection refused error code 111. This is the last couple of lines.

    ..........

    ion raise err File "/home/pickboy900/.pyenv/versions/3.7.2/lib/python3.7/socket.py", line 716, in create_connection sock.connect(sa) ConnectionRefusedError: [Errno 111] Connection refused

    Just give me a clue so that I can figure out the solution.

    Your tutorial is great. In fact best what I have ever found.

    Thanks

  • #135 Miguel Grinberg said 2019-05-09T14:39:52Z

    @Maruf: are you sure your connection details match the configuration of the debugging SMTP server? The error appears to indicate you are trying to connect to another server, or you are using an incorrect configuration for this server.

  • #136 Jonathan George said 2019-05-14T03:29:56Z

    hi, im having trouble with setting up an email, Im not sure what to do about the smtp extention not being supported by server. did i miss something from an older chapter?

    below is the error message i get:

    mail.send(msg) Traceback (most recent call last): File "", line 1, in File "c:\users\jonathan\microblog\venv\lib\site-packages\flask_mail.py", line 491, in send with self.connect() as connection: File "c:\users\jonathan\microblog\venv\lib\site-packages\flask_mail.py", line 144, in enter self.host = self.configure_host() File "c:\users\jonathan\microblog\venv\lib\site-packages\flask_mail.py", line 165, in configure_host host.login(self.mail.username, self.mail.password) File "C:\Users\Jonathan\AppData\Local\Programs\Python\Python37-32\lib\smtplib.py", line 697, in login "SMTP AUTH extension not supported by server.") smtplib.SMTPNotSupportedError: SMTP AUTH extension not supported by server.

    thanks for any help you can give.

  • #137 Miguel Grinberg said 2019-05-14T10:40:56Z

    @Jonathan: maybe use a different server, or use this same server without setting authentication credentials if the server is okay with that.

  • #138 Nicholas said 2019-08-02T18:02:39Z

    @Miguel

    Thanks again for this wonderful tutorial.

    I see a lot of people have run into the same problem as me with the "smtplib.SMTPServerDisconnected: please run connect() first" error. I have tried using localhost and my gmail but both have given me this same error. Did you ever find a workaround? Do you know of a guide on dealing with server settings? I don't know what to do here.

  • #139 nicholas.brewer90@gmail.com said 2019-08-02T18:45:55Z

    @Miguel Okay so I figured out how to get localserver working with the error. For anyone else who is having problems with it they must set the variables in the same terminal as the DebuggingServer before starting it so like

    set MAIL_SERVER=localhost set MAIL_PORT=8025 python -m smtpd -n -c DebuggingServer localhost:8025

    If I figure out how to get gmail working I will leave another comment.

  • #140 Miguel Grinberg said 2019-08-02T21:41:12Z

    @Nicholas: I'm not sure what difference does it make setting the variables in the terminal that you run the SMTP debugging server. This terminal does not run the Python code, and these variables only make sense there.

  • #141 Nicholas said 2019-08-03T14:10:03Z

    @Miguel

    Maybe it was something else that ended up getting it to work, but those are the steps I took before it actually worked.

    Now I'm running into a different error.

    Error: While importing "microblog", an ImportError was raised:

    Traceback (most recent call last): File "c:\users\shado\python-scripts\microblog\venv\lib\site-packages\flask\cli.py", line 240, in locate_app import(module_name) File "C:\Users\shado\python-scripts\microblog\microblog.py", line 1, in from app import app, db File "C:\Users\shado\python-scripts\microblog\app__init__.py", line 46, in from app import routes, models, errors File "C:\Users\shado\python-scripts\microblog\app\routes.py", line 5, in from app.emails import send_password_reset_email ModuleNotFoundError: No module named 'app.email'

    Do you have any idea what might be wrong?

  • #142 Miguel Grinberg said 2019-08-03T16:25:18Z

    @Nicholas: do you have email.py in the app package? I also find it odd that your code says "app.emails" but the error message is about "app.email". Typo when writing your comment?

  • #143 Nicholas said 2019-08-03T17:14:51Z

    @Miguel

    Oops, I tried changing "email.py" to "emails.py" to see if it was something conflicting with another Python package and in my comment I thought it would be less confusing if I reverted it to the original name you used in the tutorial. I forgot to remove the 's' in that line 5 error. It's the same error for email.py anyway (it's the same file).

    email.py is in the app package, just like you have it on GitHub.

  • #144 Miguel Grinberg said 2019-08-03T22:50:04Z

    @Nicholas: do you get the same error if you install my code? There's got to be something that's different.

  • #145 Nicholas said 2019-08-04T00:19:58Z

    @Miguel

    Well, major yet simple mistake. I didn't have email.py in the app directory. Thank you for the help.

  • #146 Thomas Svenson said 2019-08-13T19:14:22Z

    It seems flask_mail (v0.9.1) have changed its API.

    In email.py/send_password_reset_email() I had to change "html_body=" to "text_html=" to get it to work.

    Thanks for a great tutorial :)

  • #147 entangle said 2019-08-14T14:20:26Z

    this is a quite good tutorial

  • #148 Andy Gimblett said 2019-08-21T15:56:40Z

    Hi Miguel,

    I just wanted to share that I'm using smtpd.DebuggingServer as you suggest and I'm getting the same "smtplib.SMTPServerDisconnected: please run connect() first" error that Anthony reported in comment 18 in this thread; I saw your reply but I thought you might be interested that I'm following the letter of the tutorial, using an email server you suggested, and hitting the error nonetheless. This is python 3.7.3, FWIW.

    In other news, I'll join the hail of thanks for the great tutorial. :-)

    smtpd -n -c DebuggingServer

  • #149 Richard said 2019-09-10T23:03:39Z

    Hi Miguel, thanks for producing such a high quality set of tutorials, I'm enjoying going through them and am gradually becoming more familiar with the syntax. I'm using Notepad++ for editing files and Windows CMD for executing the code. I've reached the point (chapter 10) where I need to execute a number of commands to set environmental values ahead of the Flask Run (see below). Is there a way these can be housed in a single file or .py file that is invoked first thing?

    python -m venv venv venv\Scripts\activate cd PycharmProjects/EETC1

    set MAIL_SERVER=smtp.googlemail.com set MAIL_PORT=587 set MAIL_USE_TLS=1 set MAIL_USERNAME= set MAIL_PASSWORD=

    PS, I intend to watch your PYCharm video at some point to transfer development to that.

  • #150 Miguel Grinberg said 2019-09-13T12:18:11Z

    @Richard: This is covered later in the deployment chapters, but yes, you can put all your environment variables in a .env file and as long as you have the python-dotenv package installed Flask will automatically import those variables at start up.

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