old_contents: # Copyright 2016 Google Inc. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  # [START app]
  import logging
  import os
  
  from flask import Flask, render_template, request
  # [start config]
  import mailjet_rest
  
  MAILJET_API_KEY = os.environ['MAILJET_API_KEY']
  MAILJET_API_SECRET = os.environ['MAILJET_API_SECRET']
  MAILJET_SENDER = os.environ['MAILJET_SENDER']
  # [END config]
  
  app = Flask(__name__)
  
  
  # [START send_message]
  def send_message(to):
      client = mailjet_rest.Client(
          auth=(MAILJET_API_KEY, MAILJET_API_SECRET))
  
      data = {
          'FromEmail': MAILJET_SENDER,
          'FromName': 'App Engine Flex Mailjet Sample',
          'Subject': 'Example email.',
          'Text-part': 'This is an example email.',
          'Html-part': 'This is an <i>example</i> email.',
          'Recipients': [{'Email': to}]
      }
  
      result = client.send.create(data=data)
  
      return result.json()
  # [END send_message]
  
  
  @app.route('/')
  def index():
      return render_template('index.html')
  
  
  @app.route('/send/email', methods=['POST'])
  def send_email():
      to = request.form.get('to')
  
      result = send_message(to)
  
      return 'Email sent, response: <pre>{}</pre>'.format(result)
  
  
  @app.errorhandler(500)
  def server_error(e):
      logging.exception('An error occurred during a request.')
      return """
      An internal error occurred: <pre>{}</pre>
      See logs for full stacktrace.
      """.format(e), 500
  
  
  if __name__ == '__main__':
      # This is used when running locally. Gunicorn is used to run the
      # application on Google App Engine. See entrypoint in app.yaml.
      app.run(host='127.0.0.1', port=8080, debug=True)
  # [END app]
  
new_contents: # Copyright 2016 Google Inc. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  # [START app]
  import logging
  import os
  
  from flask import Flask, render_template, request
  # [START config]
  import mailjet_rest
  
  MAILJET_API_KEY = os.environ['MAILJET_API_KEY']
  MAILJET_API_SECRET = os.environ['MAILJET_API_SECRET']
  MAILJET_SENDER = os.environ['MAILJET_SENDER']
  # [END config]
  
  app = Flask(__name__)
  
  
  # [START send_message]
  def send_message(to):
      client = mailjet_rest.Client(
          auth=(MAILJET_API_KEY, MAILJET_API_SECRET))
  
      data = {
          'FromEmail': MAILJET_SENDER,
          'FromName': 'App Engine Flex Mailjet Sample',
          'Subject': 'Example email.',
          'Text-part': 'This is an example email.',
          'Html-part': 'This is an <i>example</i> email.',
          'Recipients': [{'Email': to}]
      }
  
      result = client.send.create(data=data)
  
      return result.json()
  # [END send_message]
  
  
  @app.route('/')
  def index():
      return render_template('index.html')
  
  
  @app.route('/send/email', methods=['POST'])
  def send_email():
      to = request.form.get('to')
  
      result = send_message(to)
  
      return 'Email sent, response: <pre>{}</pre>'.format(result)
  
  
  @app.errorhandler(500)
  def server_error(e):
      logging.exception('An error occurred during a request.')
      return """
      An internal error occurred: <pre>{}</pre>
      See logs for full stacktrace.
      """.format(e), 500
  
  
  if __name__ == '__main__':
      # This is used when running locally. Gunicorn is used to run the
      # application on Google App Engine. See entrypoint in app.yaml.
      app.run(host='127.0.0.1', port=8080, debug=True)
  # [END app]
  
subject: Update main.py (#337)