How do I send attachments using SMTP?

Question

I want to write a program that sends email using Python\'s smtplib. I searched through the document and the RFCs, but couldn\'t find anything related to attachments. Thus,

Answer 1

Here's how to send e-mails with zip file attachments and utf-8 encoded subject+body.

It was not straightforward to figure this one out, due to lack of documentation and samples for this particular case.

Non-ascii characters in replyto needs to be encoded with, for instance, ISO-8859-1. There probably exists a function that can do this.

Tip:
Send yourself an e-mail, save it and examine the content to figure out how to do the same thing in Python.

Here's the code, for Python 3:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# vim:set ts=4 sw=4 et:

from os.path import basename
from smtplib import SMTP
from email.mime.text import MIMEText
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.header import Header
from email.utils import parseaddr, formataddr
from base64 import encodebytes

def send_email(recipients=["somebody@somewhere.xyz"],
         subject="Test subject æøå",
         body="Test body æøå",
         zipfiles=[],
         server="smtp.somewhere.xyz",
         username="bob",
         password="password123",
         sender="Bob ",
         replyto="=?ISO-8859-1?Q?M=F8=F8=F8?= "): #: bool
    """Sends an e-mail"""
    to = ",".join(recipients)
    charset = "utf-8"
    # Testing if body can be encoded with the charset
    try:
        body.encode(charset)
    except UnicodeEncodeError:
        print("Could not encode " + body + " as " + charset + ".")
        return False

    # Split real name (which is optional) and email address parts
    sender_name, sender_addr = parseaddr(sender)
    replyto_name, replyto_addr = parseaddr(replyto)

    sender_name = str(Header(sender_name, charset))
    replyto_name = str(Header(replyto_name, charset))

    # Create the message ('plain' stands for Content-Type: text/plain)
    try:
        msgtext = MIMEText(body.encode(charset), 'plain', charset)
    except TypeError:
        print("MIMEText fail")
        return False

    msg = MIMEMultipart()

    msg['From'] = formataddr((sender_name, sender_addr))
    msg['To'] = to #formataddr((recipient_name, recipient_addr))
    msg['Reply-to'] = formataddr((replyto_name, replyto_addr))
    msg['Subject'] = Header(subject, charset)

    msg.attach(msgtext)

    for zipfile in zipfiles:
        part = MIMEBase('application', "zip")
        b = open(zipfile, "rb").read()
        # Convert from bytes to a base64-encoded ascii string
        bs = encodebytes(b).decode()
        # Add the ascii-string to the payload
        part.set_payload(bs)
        # Tell the e-mail client that we're using base 64
        part.add_header('Content-Transfer-Encoding', 'base64')
        part.add_header('Content-Disposition', 'attachment; filename="%s"' %
                        os.path.basename(zipfile))
        msg.attach(part)

    s = SMTP()
    try:
        s.connect(server)
    except:
        print("Could not connect to smtp server: " + server)
        return False

    if username:
        s.login(username, password)
    print("Sending the e-mail")
    s.sendmail(sender, recipients, msg.as_string())
    s.quit()
    return True

def main():
    send_email()

if __name__ == "__main__":
    main()