input: def send_automated_emails(recipient_emails: List[str], sender_email: str, password: str) -> None:
      """
      Sends an automated email to each address in the provided list of recipient emails.
      Uses the provided sender email and password to authenticate and send the emails.
      
      >>> send_automated_emails(["email1@example.com", "email2@example.com"], "example@gmail.com", "example_password")
      Email sent successfully.
      Email sent successfully.
      """
output:     import smtplib
      from email.mime.text import MIMEText
      from email.mime.multipart import MIMEMultipart
  
      for recipient in recipient_emails:
          msg = MIMEMultipart()
          msg['From'] = sender_email
          msg['To'] = recipient
          msg['Subject'] = "Automated Email"
  
          body = "This is an automated email sent to you."
          msg.attach(MIMEText(body, 'plain'))
  
          server = smtplib.SMTP('smtp.gmail.com', 587)
          server.starttls()
          server.login(sender_email, password)
          text = msg.as_string()
          server.sendmail(sender_email, recipient, text)
          server.quit()
          print("Email sent successfully.")