Automatically reply to unread and unanswered messages in Python

autoreplyer.py

"""
Automatically replies to mails both unread and unanswered.

WARNING: This answers to any both unread and unanswered mail, even if it is years old.
         Don’t use on a mailbox with old messages left unread and unanswered.

Simply subclass ``AutoReplyer``, define the undefined class attribute,
and call the ``run`` method on an instance. This loops until you stop the script
(using Ctrl+C, typically) or until an error occurs, like a network failure.

Example usage:

    from autoreplyer import AutoReplyer

    class YourAutoReplyer(AutoReplyer):
        imap_server = 'your.imap.server'
        imap_port = 1234  # Custom port, only use if the default one doesn’t work.
        imap_user = 'your.imap.user@may-be-the-email-or-not.com'
        imap_password = 'your_password'

        smtp_server = 'your.smtp.server'
        smtp_port = 5678  # Custom port, only use if the default one doesn’t work.
        smtp_user = 'your.smtp.user@may-be-the-email-or-not.com'
        smtp_password = 'your_password'

        from_address = 'Your Displayed Name <your-email@address.com>'
        body = '''
        Hello,

        I’m on vacation until a date I should mention here.
        You’ll have an answer when I’m back.
        Call Django in case of emergency.

        Have a nice day,
        You
        '''
        body_html = '''
        <p>Hello</p>,

        <p>
            I’m on vacation until a date I should mention here.<br />
            You’ll have an answer when I’m back.<br />
            Call <a href="tel:+1234567890">Django</a> in case of emergency.
        </p>

        <p>
            Have a nice day,<br />
            You
        </p>
        '''

    YourAutoReplyer().run()
"""

from email import message_from_bytes
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import make_msgid
from imaplib import IMAP4, IMAP4_SSL, IMAP4_PORT, IMAP4_SSL_PORT
from smtplib import SMTP, SMTP_SSL, SMTP_PORT, SMTP_SSL_PORT
from subprocess import call
from textwrap import dedent
from time import sleep


__author__ = 'Bertrand Bordage'
__copyright__ = 'Copyright © 2016 Bertrand Bordage'
__license__ = 'MIT'


class AutoReplyer:
    refresh_delay = 5  # seconds

    imap_server = None
    imap_use_ssl = False
    imap_port = IMAP4_PORT
    imap_ssl_port = IMAP4_SSL_PORT
    imap_user = None
    imap_password = None

    smtp_server = None
    smtp_use_ssl = False
    smtp_port = SMTP_PORT
    smtp_ssl_port = SMTP_SSL_PORT
    smtp_user = None
    smtp_password = None

    from_address = None
    body = None
    body_html = None

    def __init__(self):
        if self.imap_use_ssl:
            self.imap = IMAP4_SSL(self.imap_server, self.imap_ssl_port)
        else:
            self.imap = IMAP4(self.imap_server, self.imap_port)
        self.imap.login(self.imap_user, self.imap_password)
        if self.smtp_use_ssl:
            self.smtp = SMTP_SSL(self.smtp_server, self.smtp_ssl_port)
        else:
            self.smtp = SMTP(self.smtp_server, self.smtp_port)
        self.smtp.login(self.smtp_user, self.smtp_password)

    def close(self):
        self.smtp.close()
        self.imap.logout()

    def create_auto_reply(self, original):
        mail = MIMEMultipart('alternative')
        mail['Message-ID'] = make_msgid()
        mail['References'] = mail['In-Reply-To'] = original['Message-ID']
        mail['Subject'] = 'Re: ' + original['Subject']
        mail['From'] = self.from_address
        mail['To'] = original['Reply-To'] or original['From']
        mail.attach(MIMEText(dedent(self.body), 'plain'))
        mail.attach(MIMEText(self.body_html, 'html'))
        return mail

    def send_auto_reply(self, original):
        self.smtp.sendmail(
            self.from_address, [original['From']],
            self.create_auto_reply(original).as_bytes())
        log = 'Replied to “%s” for the mail “%s”' % (original['From'],
                                                     original['Subject'])
        print(log)
        try:
            call(['notify-send', log])
        except FileNotFoundError:
            pass

    def reply(self, mail_number):
        self.imap.select(readonly=True)
        _, data = self.imap.fetch(mail_number, '(RFC822)')
        self.imap.close()
        self.send_auto_reply(message_from_bytes(data[0][1]))
        self.imap.select(readonly=False)
        self.imap.store(mail_number, '+FLAGS', '\\Answered')
        self.imap.close()

    def check_mails(self):
        self.imap.select(readonly=False)
        _, data = self.imap.search(None, '(UNSEEN UNANSWERED)')
        self.imap.close()
        for mail_number in data[0].split():
            self.reply(mail_number)

    def run(self):
        try:
            while True:
                self.check_mails()
                sleep(self.refresh_delay)
        finally:
            self.close()