input: Write a python function to send an email using smtplib.
  assert send_email('sender@gmail.com', 'reciever@gmail.com', 'my-password', 'Welcome to our website!', 'Thank you for visiting our website!') == "Email sent successfully"
  assert send_email('sender@gmail.com', 'reciever@gmail.com', 'wrong-password', 'Welcome to our website!', 'Thank you for visiting our website!') == "Failed to send email"
  assert send_email('sender@gmail.com', 'invalid-email', 'my-password', 'Welcome to our website!', 'Thank you for visiting our website!') == "Failed to send email"
output: import smtplib
  from email.mime.text import MIMEText
  from email.mime.multipart import MIMEMultipart
  
  def send_email(sender_email, receiver_email, password, subject, body):
      try:
          # Set up the MIME
          message = MIMEMultipart()
          message['From'] = sender_email
          message['To'] = receiver_email
          message['Subject'] = subject
  
          # Add body to email
          message.attach(MIMEText(body, 'plain'))
  
          # Create SMTP session for sending the mail
          server = smtplib.SMTP('smtp.gmail.com', 587)
          server.starttls()  # enable security
          server.login(sender_email, password)  # login with mail_id and password
  
          text = message.as_string()
          server.sendmail(sender_email, receiver_email, text)
          server.quit()
          return "Email sent successfully"
      except:
          return "Failed to send email"