email_monitor.py

#!/usr/bin/env python
import os
import sys
import imaplib
import email
import email.header
import datetime
import boto3


EMAIL_ACCOUNT = os.environ['EMAIL_ACCOUNT']
EMAIL_PASSWORD = os.environ['EMAIL_PASSWORD']

# Use 'INBOX' to read inbox.  Note that whatever folder is specified, 
# after successfully running this script all emails in that folder 
# will be marked as read.

EMAIL_FOLDER = os.environ['EMAIL_FOLDER']

AWS_REGION = os.environ['X_AWS_REGION']
AWS_ACCESS_KEY_ID = os.environ['X_AWS_ACCESS_KEY_ID']
AWS_SECRET_KEY = os.environ['X_AWS_SECRET_KEY']
AWS_METRIC_NAME = os.environ['AWS_METRIC_NAME']
AWS_CLOUDWATCH_NAMESPACE = os.environ['AWS_CLOUDWATCH_NAMESPACE']


def chunks(l, n):
    """Yield successive n-sized chunks from l."""
    for i in range(0, len(l), n):
        yield l[i:i + n]


def process_mailbox(M):
    """
    Do something with emails messages in the folder.  
    For the sake of this example, print some headers.
    """

    rv, data = M.search(None, '(UNSEEN)')
    if rv != 'OK':
        print("No messages found!")
        return

    all_metrics = []

    for num in data[0].split():
        rv, data = M.fetch(num, '(RFC822)')
        if rv != 'OK':
            print("ERROR getting message", num)
            return

        msg = email.message_from_bytes(data[0][1])
        hdr = email.header.make_header(email.header.decode_header(msg['Subject']))
        subject = str(hdr)
        non_ascii_subject =  ''.join([i if ord(i) < 128 else ' ' for i in subject])
        msg_date = msg['Date']
        time_stamp = datetime.datetime.strptime(msg_date, '%a, %d %b %Y %H:%M:%S %z')

        print('Message %s: %s' % (num, subject))
        print('Raw Date:', msg_date)
        all_metrics.append(
            {
                'MetricName': AWS_METRIC_NAME,
                'Dimensions': [
                    {
                        'Name': 'EmailAccount',
                        'Value': EMAIL_ACCOUNT
                    },
                    {
                        'Name': 'Subject',
                        'Value': non_ascii_subject
                    },
                ],
                'Timestamp': time_stamp,
                'Value': 1,
                'Unit': 'Count',
            },
        )
    return all_metrics


def lambda_handler(event, context):
    M = imaplib.IMAP4_SSL('imap.gmail.com')

    try:
        rv, data = M.login(EMAIL_ACCOUNT, EMAIL_PASSWORD)
    except imaplib.IMAP4.error:
        print ("LOGIN FAILED!!! ")
        sys.exit(1)

    print(rv, data)

    rv, mailboxes = M.list()
    if rv == 'OK':
        print("Mailboxes:")
        print(mailboxes)

    rv, data = M.select(EMAIL_FOLDER)
    if rv == 'OK':
        print("Processing mailbox...\n")
        all_metrics = process_mailbox(M)
        print("Metrics to be sent to AWS (namespace = {}): {}".format(AWS_CLOUDWATCH_NAMESPACE, all_metrics))
    
        cloudwatch = boto3.client(
            'cloudwatch',
            region_name=AWS_REGION,
            aws_access_key_id=AWS_ACCESS_KEY_ID,
            aws_secret_access_key=AWS_SECRET_KEY,
        )
        for metric_data in list(chunks(all_metrics, 10)):
            response = cloudwatch.put_metric_data(
                Namespace=AWS_CLOUDWATCH_NAMESPACE,
                MetricData=metric_data
            )
            print("Response from AWS: {}".format(response))

        M.close()
    else:
        print("ERROR: Unable to open mailbox ", rv)

    M.logout()

This is a script I used to check email received. Our CI server would run daily tests, and those test would send out emails. If no email was detected in our test mailbox, I had cloudwatch configured to send and alarm email to the support team