function sanitize_email( $email ) {
  // Test for the minimum length the email can be.
  if ( strlen( $email ) < 6 ) {
    
/**
 * Filters a sanitized email address.
 *
 * This filter is evaluated under several contexts, including 'email_too_short',
 * 'email_no_at', 'local_invalid_chars', 'domain_period_sequence', 'domain_period_limits',
 * 'domain_no_periods', 'domain_no_valid_subs', or no context.
 *
 * @since 2.8.0
 *
 * @param string $sanitized_email The sanitized email address.
 * @param string $email           The email address, as provided to sanitize_email().
 * @param string|null $message    A message to pass to the user. null if email is sanitized.
 */
    return apply_filters( 'sanitize_email', '', $email, 'email_too_short' );
  }

  // Test for an @ character after the first position.
  if ( strpos( $email, '@', 1 ) === false ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'email_no_at' );
  }

  // Split out the local and domain parts.
  list( $local, $domain ) = explode( '@', $email, 2 );

  /*
	 * LOCAL PART
	 * Test for invalid characters.
	 */
  $local = preg_replace( '/[^a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]/', '', $local );
  if ( '' === $local ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'local_invalid_chars' );
  }

  /*
	 * DOMAIN PART
	 * Test for sequences of periods.
	 */
  $domain = preg_replace( '/\.{2,}/', '', $domain );
  if ( '' === $domain ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'domain_period_sequence' );
  }

  // Test for leading and trailing periods and whitespace.
  $domain = trim( $domain, " \t\n\r\0\x0B." );
  if ( '' === $domain ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'domain_period_limits' );
  }

  // Split the domain into subs.
  $subs = explode( '.', $domain );

  // Assume the domain will have at least two subs.
  if ( 2 > count( $subs ) ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'domain_no_periods' );
  }

  // Create an array that will contain valid subs.
  $new_subs = array();

  // Loop through each sub.
  foreach ( $subs as $sub ) {
    // Test for leading and trailing hyphens.
    $sub = trim( $sub, " \t\n\r\0\x0B-" );

    // Test for invalid characters.
    $sub = preg_replace( '/[^a-z0-9-]+/i', '', $sub );

    // If there's anything left, add it to the valid subs.
    if ( '' !== $sub ) {
      $new_subs[] = $sub;
    }
  }

  // If there aren't 2 or more valid subs.
  if ( 2 > count( $new_subs ) ) {
    
/** This filter is documented in wp-includes/formatting.php */
    return apply_filters( 'sanitize_email', '', $email, 'domain_no_valid_subs' );
  }

  // Join valid subs into the new domain.
  $domain = implode( '.', $new_subs );

  // Put the email back together.
  $sanitized_email = $local . '@' . $domain;

  // Congratulations, your email made it!