public function check_customer_coupons( $posted ) {
		foreach ( $this->get_applied_coupons() as $code ) {
			$coupon = new WC_Coupon( $code );

			if ( $coupon->is_valid() ) {

				// Get user and posted emails to compare.
				$current_user  = wp_get_current_user();
				$billing_email = isset( $posted['billing_email'] ) ? $posted['billing_email'] : '';
				$check_emails  = array_unique(
					array_filter(
						array_map(
							'strtolower',
							array_map(
								'sanitize_email',
								array(
									$billing_email,
									$current_user->user_email,
								)
							)
						)
					)
				);

				// Limit to defined email addresses.
				$restrictions = $coupon->get_email_restrictions();

				if ( is_array( $restrictions ) && 0 < count( $restrictions ) && ! $this->is_coupon_emails_allowed( $check_emails, $restrictions ) ) {
					$coupon->add_coupon_message( WC_Coupon::E_WC_COUPON_NOT_YOURS_REMOVED );
					$this->remove_coupon( $code );
				}

				$coupon_usage_limit = $coupon->get_usage_limit_per_user();
				if ( 0 < $coupon_usage_limit && 0 === get_current_user_id() ) {
					// For guest, usage per user has not been enforced yet. Enforce it now.
					$coupon_data_store = $coupon->get_data_store();
					$billing_email = strtolower( sanitize_email( $billing_email ) );
					if ( $coupon_data_store && $coupon_data_store->get_usage_by_email( $coupon, $billing_email ) >= $coupon_usage_limit ) {
						$coupon->add_coupon_message( WC_Coupon::E_WC_COUPON_USAGE_LIMIT_REACHED );
					}
				}
			}
		}
	}