Python Gmail API parsing message body and sending with Flask

I'm working on Gmail message parser which will be putting certain parts of message to json. If I'm returning only one value message_body from get_message() everythings works perferct. When message is unread I've got body of that message. And next time when message is marked as readed I've got null which is perfect. How can I modify my code to sending this two values separetly when message is unread and next time when message is marked as readed getting 'null`?

Here is my code for getting mesage

from apiclient import discovery
from httplib2 import Http
from oauth2client import file, client, tools
import dateutil.parser as parser
import re


def get_message():

    SCOPES = 'https://www.googleapis.com/auth/gmail.modify'

    store = file.Storage('storage.json')
    creds = store.get()
    if not creds or creds.invalid:
        flow = client.flow_from_clientsecrets('client_secret.json', SCOPES)
        creds = tools.run_flow(flow, store)
    GMAIL = discovery.build('gmail', 'v1', http=creds.authorize(Http()))

    user_id = 'me'
    label_id_one = 'INBOX'
    label_id_two = 'UNREAD'


    unread_msgs = GMAIL.users().messages().list(userId='me', labelIds=[label_id_one, label_id_two]).execute()

    mssg_list = unread_msgs.get('messages')

    try:
        for mssg in mssg_list:
            temp_dict = {}
            m_id = mssg['id']
            message = GMAIL.users().messages().get(userId=user_id, id=m_id).execute()

            payld = message['payload']
            headr = payld['headers']

            for one in headr:
                if one['name'] == 'Subject':
                    msg_subject = one['value']
                    temp_dict['Subject'] = msg_subject
                else:
                    pass

            for two in headr:
                if two['name'] == 'Date':
                    msg_date = two['value']
                    date_parse = (parser.parse(msg_date))
                    m_date = (date_parse.date())
                    temp_dict['Date'] = str(m_date)
                else:
                    pass

            for three in headr:
                if three['name'] == 'From':
                    msg_from = three['value']
                    temp_dict['Sender'] = msg_from
                else:
                    pass

            temp_dict['Snippet'] = message['snippet']

            final_message = message['snippet']

            regex_message_body = re.compile('^.+?(?=Sender)')
            regex_message_sender = re.compile('(?=(\+\d*))')

            message = regex_message_body.findall(final_message)
            if len(message) > 0:
                message_body = message[0]
                print(message_body)

            sender = regex_message_sender.findall(final_message)
            if len(sender) > 0:
                message_sender = sender[0]
                # print(message_sender)

            # Marking message as read
            GMAIL.users().messages().modify(userId=user_id, id=m_id, body={'removeLabelIds': ['UNREAD']}).execute()
            return message_body, message_sender
    except TypeError:
        print('No new messages')

Here is my code for API

@app.route('/messages', methods=['GET'])
def message():
    return jsonify({'Content-Type': 'application/json', 'id': random.uniform(0, 1), 'sender': ????, 'timestamp': '{:%Y-%m-%d %H:%M:%S}'.format(datetime.datetime.now()), 'message': ???})