Python SMTP Email Code - How to Send HTML Email from Python Code with Authentication at SMTP Server

from smtplib import SMTP_SSL as SMTP
from email.mime.multipart import MIMEMultipart

from email.mime.text import MIMEText

class EmailClient:
  def __init__(self):
    self._mail_server = '<Your-email-smtp-server>'
    self._mail_server_port = 587 # <smtp-server port number>
    self._sender = "<sender email address>"
    self._credentials = {
      "username": "<sender email address>",
      "password": "<password>"
    }

  def send_mail(self, recipients, subject, email_body):    
    msg = MIMEMultipart()
    body = MIMEText(email_body, 'html')
    msg['Subject'] = subject
    msg.attach(body)

    with SMTP(self._mail_server,port=self._mail_server_port) as conn:
      conn.login(self._credentials['username'], self._credentials['password'])

      conn.sendmail(self._sender, recipients, msg.as_string())