[Python] How to use SMTP with Apple iCloud Custom Domain

I would like to use Python's SMTP to send automated emails with a custom domain iCloud+ email address. However, I can't get logged into the SMTP servers. I will always either get "Mailbox does not exist" or "Authentication failed".

From the Apple support pages it seems like you need to use SSL over port 587. Additionally, they want you to generate an "app-specific password" for outside applications. This led me to the following code:

import smtplib, ssl

smtp_server = "smtp.mail.me.com"
port = 587 # For SSL

# Create a secure SSL context
context = ssl.create_default_context()

sender_email = "me@example.com" # Enter your address
receiver_email = "you@example.com" # Enter receiver address
password = "some,password" # app specific password from Apple ID settings
message = """\
To: {to}
From: {sender}
Subject: Hello There

This was sent through Python!
""".format(to=receiver_email, sender=sender_email)

with smtplib.SMTP_SSL(smtp_server, port, context=context) as server:
server.login(sender_email, password)
# Send email here
server.sendmail(sender_email, receiver_email, message)


However, this was still giving me a connection error. Only when I changed the last part to use TLS instead would it connect and give me an authentication error. This was taken from this question: SMTP_SSL SSLError: [SSL: UNKNOWN_PROTOCOL] unknown protocol (_ssl.c:590)

try:
server = smtplib.SMTP(smtp_server, port)
server.ehlo() # Can be omitted
server.starttls(context=context) # Secure the connection
server.ehlo() # Can be omitted
server.login(sender_email, password)
# Send email here
server.sendmail(sender_email, receiver_email, message)
except Exception as e:
import traceback
print(traceback.format_exc())
finally:
server.quit()


So how can I use my custom domain address with Apple's iCloud+ service with Python's SMTP?

Continue reading...