checkmail.py

#!/usr/bin/env python

from imapclient import IMAPClient
import time

import RPi.GPIO as GPIO

DEBUG = True

HOSTNAME = 'imap.gmail.com'
USERNAME = 'your username here'
PASSWORD = 'your password here'
MAILBOX = 'Inbox'

NEWMAIL_OFFSET = 1   # my unread messages never goes to zero, yours might
MAIL_CHECK_FREQ = 60 # check mail every 60 seconds

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GREEN_LED = 18
RED_LED = 23
GPIO.setup(GREEN_LED, GPIO.OUT)
GPIO.setup(RED_LED, GPIO.OUT)

while True:
    server = IMAPClient(HOSTNAME, use_uid=True, ssl=True)
    server.login(USERNAME, PASSWORD)

    if DEBUG:
        print('Logging in as ' + USERNAME)
        select_info = server.select_folder(MAILBOX)
        print('%d messages in INBOX' % select_info['EXISTS'])

    folder_status = server.folder_status(MAILBOX, 'UNSEEN')
    newmails = int(folder_status['UNSEEN'])

    if DEBUG:
        print "You have", newmails, "new emails!"

    if newmails > NEWMAIL_OFFSET:
        GPIO.output(GREEN_LED, True)
        GPIO.output(RED_LED, False)
    else:
        GPIO.output(GREEN_LED, False)
        GPIO.output(RED_LED, True)

    time.sleep(MAIL_CHECK_FREQ)

GPIO.cleanup()