Flask-Mail not Authenticating with Gmail and App password - python-2.7

Question

So I am getting an SMTPSenderRefused error when I try to use the flask app I built to send an email. Let me start buy saying this worked previously but now it has stopped. I am at a loss and I have spent many hours testing and tweaking and reading online and NOTHING has given me an answer.
I keep getting the following error.
[2019-01-21 03:07:51,954] ERROR in app: Exception on /register/ [POST]
Traceback (most recent call last):
File "/usr/local/lib/python2.7/site-packages/flask/app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python2.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python2.7/site-packages/flask/app.py", line 1718, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python2.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python2.7/site-packages/flask/app.py", line 1799, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "MyFlaskApp.py", line 131, in register
mail.send(msg)
File "/usr/local/lib/python2.7/site-packages/flask_mail.py", line 492, in send
message.send(connection)
File "/usr/local/lib/python2.7/site-packages/flask_mail.py", line 427, in send
connection.send(self)
File "/usr/local/lib/python2.7/site-packages/flask_mail.py", line 192, in send
message.rcpt_options)
File "/usr/lib64/python2.7/smtplib.py", line 737, in sendmail
raise SMTPSenderRefused(code, resp, from_addr)
SMTPSenderRefused: (530, '5.5.1 Authentication Required. Learn more at\n5.5.1 https://support.google.com/mail/?p=WantAuthError u186sm20332024pfu.51 - gsmtp', u'myemail#gmail.com')
IP.XX.XXX.XXX - - [21/Jan/2019 03:07:51] "POST /register/ HTTP/1.1" 500 -
My gmail account is configured with 2 step verification and then an application password that this Flask App uses. I have tried every combination and it still will not work. This is my code that I am using.
app = Flask(__name__, static_url_path='/static')
app.config.update(
DEBUG = False,
MAIL_SERVER = 'smtp.gmail.com',
MAIL_PORT = 465,
MAIL_USE_SSL = True,
MAIL_USERNAME = 'myemail#gmail.com',
MAIL_DEFAULT_SENDER = 'myemail#gmail.com',
MAIL_PASSWORD = 'GmailApplicationPassword',
)
mail = Mail(app)
The lines to actually send the message (inside the POST):
msg = Message("Welcome",
sender = 'myemail#gmail.com',
recipients = [request.form["email"]])
msg.body = "Welcome! \n\n Congratulations on your successful registration. \n\n Cheers!"
mail.send(msg)
Some additional information that might be helpful. This exact code used to work when I was running my application locally. Then I deployed my code to my AWS EC2 instance and had it working on there. It was working until I did the following.
I associated a Elastic IP address with the site and then pointed my DNS to that IPv4. I have also added AWS Public Certificate.
Can someone please help me understand why I am unable to send emails. I have tried everything I can find as solutions online.
Additional Details:
$ pip freeze
Flask-Mail==0.9.1
Thanks in advance and I will help provide any answers if more clarification is needed so please ask.

Answer 1

This is the solution that I found to work best. (I am not saying this is the best method but it works) It involves the use of a few different key concepts that I would Highly Recommend using. It involves the use of secrets, which you can follow this guide here for more information on this (as it is not the heart of this question I will only leave a link here). It also required the use of Boto3 to be able to read the variables. The AWS documentation will be helpful here so again I am not including it.
My method was to set up AWS Simple Email Service (SES). This makes it such that the application using Flask-Mail accesses AWS SES to send the email which then talks to gmail to actually send out the email. A few important notes here are that the SES is not in every region but presently (June 2019) it is not required that your EC2 instance be hosted in the same region that you are using SES in. Additionally, if you want to be able to send emails to outside addresses you MUST ensure that you have the email inbox configured in accordance with and not violate AWS terms of use. And Finally if you are on the free tier, you must submit a support ticket to get a rate increase and it will also allow you to send emails externally. Now here is the bit of code that I use:
app = Flask(__name__, static_url_path='/static')
app.config.update(
DEBUG = False,
MAIL_SERVER = params.getParameter("SES_SERVER"),
MAIL_PORT = 587,
MAIL_USE_TLS = True,
MAIL_USERNAME = params.getParameter("SES_USERNAME"),
MAIL_PASSWORD = params.getParameter("SES_PASSWORD"),
)
mail = Mail(app)
The sending code remains unchanged.
I did need to add the an import for Boto3 and I created a new file that is called params.py and is where I built my getParameter method to access the variables. If you want you could hard code the values above but I would not recommend it, especially if you are storing your code in a cloud repository.
I am not 100% sure but I suspect that gmail prohibits a IP address or domain from AWS accessing its servers and thus you cannot send emails. This is my suspicion but I could not find a way to prove it.

Answer 2

For gmail accounts for which 2-Step verification is activated, allowing less secure app is disabled. In that case to access App Password need to be generated.
This is app config code written in flask app.
`app = Flask(__name__)
app.config.update(
MAIL_SERVER = "smtp.gmail.com",
MAIL_PORT="465",
MAIL_USE_SSL=True,
MAIL_USERNAME=params['gmail-user'],
MAIL_PASSWORD=params['gmail-pass']
)
mail=Mail(app)`
Created "config.json" to define the parameter, which will be used above. For username and password check "gmail-user" and "gmail-pass"
{"params":
{ "local_server":"True",
"local_uri":"mysql+pymysql://root:#localhost/jbh_datasc_blog",
"prod_uri": "mysql+pymysql://root:#localhost/jbh_datasc_blog",
"fb_url":"https://facebook.com/<give the name of extension>",
"tw_url":"https://twitter.com/<give the name of extension>",
"gh_url":"https://github.com/<give the name of extension>",
"blog_head":"Data Science Digital",
"sub_head":"Innovating Future",
"gmail-user":"xxxxxxxx#gmail.com",
"gmail-pass":"xxxxxxxxxxxxxxxx"
}
}
Go the your gmail account and in the search bar type App Password.
It will ask about the name of app and computer from where r u accessing, provide it.
Google will generate a 16 digit password.
Use this password to fill in the 'gmail-pass'
Save and execute the code.