public function set_primary_email( $new_primary_email = '' ) {

    if( ! is_email( $new_primary_email ) ) {
      return false;
    }

    do_action( 'edd_customer_pre_set_primary_email', $new_primary_email, $this->id, $this );

    $existing = new EDD_Customer( $new_primary_email );

    if( $existing->id > 0 && (int) $existing->id !== (int) $this->id ) {

      // This email belongs to another customer
      return false;
    }

    $old_email = $this->email;

    // Update customer record with new email
    $update = $this->update( array( 'email' => $new_primary_email ) );

    // Remove new primary from list of additional emails
    $remove = $this->remove_email( $new_primary_email );

    // Add old email to additional emails list
    $add = $this->add_email( $old_email );

    $ret = $update && $remove && $add;

    if( $ret ) {

      $this->email = $new_primary_email;

      $payment_ids = $this->get_payment_ids();

      if( $payment_ids ) {

        foreach( $payment_ids as $payment_id ) {

          // Update payment emails to primary email
          edd_update_payment_meta( $payment_id, 'email', $new_primary_email );

        }

      }
    }

    do_action( 'edd_customer_post_set_primary_email', $new_primary_email, $this->id, $this );

    return $ret;

  }