Python3 SMTP ‘Connection unexpectedly closed’

Could somebody please tell me why I am getting a SMTPServerDisconnected(“Connection unexpectedly closed”) error from the following code?

import smtplib

from string import Template

from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

MY_ADDRESS = '---'
PASSWORD = '---'

def get_contacts(filename):
"""
Return two lists names, emails containing names and email 
addresses
read from a file specified by filename.
"""

names = []
emails = []
with open(filename, mode='r', encoding='utf-8') as contacts_file:
    for a_contact in contacts_file:
        names.append(a_contact.split()[0])
        emails.append(a_contact.split()[1])
return names, emails

def read_template(filename):
"""
Returns a Template object comprising the contents of the 
file specified by filename.
"""

with open(filename, 'r', encoding='utf-8') as template_file:
    template_file_content = template_file.read()
return Template(template_file_content)

def main():
names, emails = get_contacts('contacts.txt') # read contacts
message_template = read_template('message.txt')

# set up the SMTP server
s = smtplib.SMTP('smtp.gmail.com', 465)
s.ehlo()
s.starttls()
s.login(MY_ADDRESS, PASSWORD)

# For each contact, send the email:
for name, email in zip(names, emails):
    msg = MIMEMultipart()       # create a message

    # add in the actual person name to the message template
    message = 
message_template.substitute(PERSON_NAME=name.title())

    # Prints out the message body for our sake
    print(message)

    # setup the parameters of the message
    msg['From']=MY_ADDRESS
    msg['To']=email
    msg['Subject']="This is TEST"

    # add in the message body
    msg.attach(MIMEText(message, 'plain'))

    # send the message via the server set up earlier.
    s.send_message(msg)
    del msg

# Terminate the SMTP session and close the connection
s.quit()

if __name__ == '__main__':
main()

Obviously when I run the code my address and password is filled in.

The traceback I get from this when running in terminal is:

Traceback (most recent call last):
File “emailAlert2.py”, line 71, in
main()
File “emailAlert2.py”, line 40, in main
s = smtplib.SMTP(‘smtp.gmail.com’, 465)
File “/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py”, line 251, in init
(code, msg) = self.connect(host, port)
File “/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py”, line 338, in connect
(code, msg) = self.getreply()
File “/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py”, line 394, in getreply
raise SMTPServerDisconnected(“Connection unexpectedly closed”)
smtplib.SMTPServerDisconnected: Connection unexpectedly closed

Thanks