Mass personalized email script

mass_email.py

"""Mass personalized email script"""

import sys
import smtplib
import argparse

from email import encoders
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart

HOST = 'smtp.gmail.com'
PORT = 587
RATE_LIMIT = 10 - 1

def smtp_login(username, password):
    server = smtplib.SMTP(HOST, PORT)
    server.starttls()
    try:
        server.login(username, password)
    except:
        sys.stderr.write('Error: SMTP connection failed\n')
        exit(1)
    return server

def is_text_file(name):
    if '.txt' in name:
        return True
    return False

def read_body(path):
    try:
        with open(path) as f:
            body = f.read().strip()
            return body
            f.close()
    except:
        sys.stderr.write('Error: Metadata file doesn\'t exist\n')
        exit(1)

def read_receivers(path):
    receivers = []
    try:
        with open(path) as f:
            lines = f.read().split('\n')
            for line in lines:
                tags = line.split(',')
                if len(tags) == 2:
                    receivers.append((tags[0],tags[1]))
            f.close()
    except:
        sys.stderr.write('Error: Receivers file doesn\'t exist\n')
        exit(1)
    return receivers

def read_attachment(path):
    try:
        with open(path) as f:
            pass
    except:
        sys.stderr.write('Error: Attachment file doesn\'t exist\n')
        exit(1)

def create_email(subject, body, sender, receiver, attachment):
    outer = MIMEMultipart()
    name, email = receiver

    outer['Subject'] = subject
    outer['To'] = email
    outer['From'] = sender

    message_text = body.replace('<>', name)
    outer.attach(MIMEText(message_text, 'plain'))

    attachment_file = open(attachment, 'rb')
    part = MIMEBase('application', 'octet-stream')
    part.set_payload((attachment_file).read())
    encoders.encode_base64(part)
    part.add_header(
        'Content-Disposition',
        'attachment',
        filename=attachment
    )
    outer.attach(part)
    return outer

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description="""
    Send mass personalized emails to a collection of receivers. This script
    only supports one PDF attachment and placeholder value reserved for the
    name of the receiver.

    Usage example:
    python3 mass_email.py -u username -p password -s 'Summer Internship' -b body.txt -r receivers.txt -a Resume.pdf
    """)
    parser.add_argument('-u', '--username', required=True,
                        help="""Gmail username used to authenticate
                                the SMTP sever""")
    parser.add_argument('-p', '--password', required=True,
                        help="""Gmail password used to authenciate
                                the SMTP server""")
    parser.add_argument('-s', '--subject', required=True,
                        help="""Subject of email""")
    parser.add_argument('-b', '--body', required=True,
                        help="""Name of text file containing email body.
                        Body should include <> whenever a placeholder
                        value needs to be used.
                        """)
    parser.add_argument('-r', '--receivers', required=True,
                        help="""Name of text file containing email receivers.
                        Must include receiver name and address in this form:
                            <name 1>,<address 1>
                            <name 2>,<address 2>
                            ...
                        """)
    parser.add_argument('-a', '--attachment', required=True,
                        help="""Name of PDF attachment""")
    args = parser.parse_args()

    if not is_text_file(args.body) or not is_text_file(args.receivers):
        sys.stderr.write('Error: Incorrect metadata or receiver file types\n')
        exit(1)

    subject = args.subject

    body = read_body(args.body)
    sys.stdout.write('Body file parsing successful\n')

    receivers = read_receivers(args.receivers)
    sys.stdout.write('Receivers file parsing successful\n')

    attachment = read_attachment(args.attachment)
    sys.stdout.write('Attachment file parsing successful\n')

    username, password = args.username, args.password
    server = smtp_login(username, password)
    sys.stdout.write('SMTP server authentication successful\n\n')

    for i in range(len(receivers)):
        if i == RATE_LIMIT:
            sys.stdout.write('\nGoogle SMTP rate limit exceeded. Please try ' +
                                'sending the rest of these emails tomorrow.\n')
            sys.stdout.write('You left off at {}.\n'.format(receivers[i]))
            exit(1)

        email = create_email(
            subject=subject,
            body=body,
            sender=username,
            receiver=receivers[i],
            attachment=args.attachment
        )

        text = email.as_string()

        server.sendmail(username, receivers[i][1], text)
        print('({index}/{total}) Email sent to {email}'.format(
            index=(i + 1),
            total=len(receivers),
            email=receivers[i]
        ))

    server.quit()
    exit(0)