Simple Python-Script to send Testmails over TLS (587) with authentication

sendmail-encrypted-auth.py

#!/usr/bin/env python3

import smtplib
import ssl
from email.message import EmailMessage
from pathlib import Path
from os.path import basename
from argparse import ArgumentParser

REQUIRE_FROM_DOMAIN = '@<your-domain>.xy'


def main():
    msg = EmailMessage()
    msg['Subject'] = args.subject
    msg['From'] = getattr(args, 'from')
    msg['To'] = args.to
    msg.set_content(args.body, subtype='html')

    if args.attachment is not None:
        with open(args.attachment, 'rb') as f:
            file_data = f.read()

        msg.add_attachment(
            file_data, maintype='text', subtype='plain',
            filename=args.attachment_name if args.attachment_name is not None else basename(args.attachment),
        )

    context = ssl.create_default_context()

    try:
        with smtplib.SMTP(args.server, 587) as server:
            server.ehlo()
            server.starttls(context=context)
            server.ehlo()

            if args.user and args.password:
                server.login(args.user, args.password)

            server.send_message(msg)
            print("Email sent successfully!")

    except Exception as e:
        print(f"Error: {e}")

if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument(
        '-f', '--from', required=False,
        default='[email protected]', help='From E-Mail Address',
    )
    parser.add_argument('-x', '--server', required=True, help='Server IP/DNS')
    parser.add_argument('-t', '--to', required=True, help='To E-Mail Address')
    parser.add_argument('-a', '--attachment', required=False, help='Path to attachment')
    parser.add_argument('-an', '--attachment-name', required=False, help='Name of attachment')
    parser.add_argument('-b', '--body', required=True, help='E-Mail Body')
    parser.add_argument('-s', '--subject', required=True, help='E-Mail Subject')
    parser.add_argument('-u', '--user', help='SMTP Username')
    parser.add_argument('-p', '--password', help='SMTP Password')
    args = parser.parse_args()

    if args.attachment is not None and not Path(args.attachment).is_file():
        raise FileNotFoundError(f'No such file: {args.attachment}')

    if getattr(args, 'from').find(REQUIRE_FROM_DOMAIN) == -1:
        raise FileNotFoundError(f'From domain needs to be: {REQUIRE_FROM_DOMAIN}')

    main()