WP_Automatic_Updater::send_debug_email

		$email = compact( 'to', 'subject', 'body', 'headers' );

		/**
		 * Filters the email sent following an automatic background core update.
		 *
		 * @since 3.7.0
		 *
		 * @param array $email {
		 *     Array of email arguments that will be passed to wp_mail().
		 *
		 *     @type string $to      The email recipient. An array of emails
		 *                            can be returned, as handled by wp_mail().
		 *     @type string $subject The email's subject.
		 *     @type string $body    The email message body.
		 *     @type string $headers Any email headers, defaults to no headers.
		 * }
		 * @param string $type        The type of email being sent. Can be one of
		 *                            'success', 'fail', 'manual', 'critical'.
		 * @param object $core_update The update offer that was attempted.
		 * @param mixed  $result      The result for the core update. Can be WP_Error.
		 */
		$email = apply_filters( 'auto_core_update_email', $email, $type, $core_update, $result );

		wp_mail( $email['to'], wp_specialchars_decode( $email['subject'] ), $email['body'], $email['headers'] );
	}


	/**
	 * If we tried to perform plugin or theme updates, check if we should send an email.
	 *
	 * @since 5.5.0
	 *
	 * @param array $update_results The results of update tasks.
	 */
	protected function after_plugin_theme_update( $update_results ) {
		$successful_updates = array();
		$failed_updates     = array();

		/**
		 * Filters whether to send an email following an automatic background plugin update.
		 *
		 * @since 5.5.0
		 * @since 5.5.1 Added the $update_results parameter.
		 *
		 * @param bool  $enabled        True if plugins notifications are enabled, false otherwise.
		 * @param array $update_results The results of plugins update tasks.
		 */
		$notifications_enabled = apply_filters( 'auto_plugin_update_send_email', true, $update_results['plugin'] );

		if ( ! empty( $update_results['plugin'] ) && $notifications_enabled ) {
			foreach ( $update_results['plugin'] as $update_result ) {
				if ( true === $update_result->result ) {
					$successful_updates['plugin'][] = $update_result;
				} else {
					$failed_updates['plugin'][] = $update_result;
				}
			}
		}

		/**
		 * Filters whether to send an email following an automatic background theme update.
		 *
		 * @since 5.5.0
		 * @since 5.5.1 Added the $update_results parameter.
		 *
		 * @param bool  $enabled True if notifications are enabled, false otherwise.
		 * @param array $update_results The results of theme update tasks.
		 */
		$notifications_enabled = apply_filters( 'auto_theme_update_send_email', true, $update_results['theme'] );

		if ( ! empty( $update_results['theme'] ) && $notifications_enabled ) {
			foreach ( $update_results['theme'] as $update_result ) {
				if ( true === $update_result->result ) {
					$successful_updates['theme'][] = $update_result;
				} else {
					$failed_updates['theme'][] = $update_result;
				}
			}
		}

		if ( empty( $successful_updates ) && empty( $failed_updates ) ) {
			return;
		}

		if ( empty( $failed_updates ) ) {
			$this->send_plugin_theme_email( 'success', $successful_updates, $failed_updates );
		} elseif ( empty( $successful_updates ) ) {
			$this->send_plugin_theme_email( 'fail', $successful_updates, $failed_updates );
		} else {
			$this->send_plugin_theme_email( 'mixed', $successful_updates, $failed_updates );
		}
	}

	/**
	 * Sends an email upon the completion or failure of a plugin or theme background update.
	 *
	 * @since 5.5.0
	 *
	 * @param string $type               The type of email to send. Can be one of 'success', 'fail', 'mixed'.
	 * @param array  $successful_updates A list of updates that succeeded.
	 * @param array  $failed_updates     A list of updates that failed.
	 */
	protected function send_plugin_theme_email( $type, $successful_updates, $failed_updates ) {
		// No updates were attempted.
		if ( empty( $successful_updates ) && empty( $failed_updates ) ) {
			return;
		}

		$unique_failures     = false;
		$past_failure_emails = get_option( 'auto_plugin_theme_update_emails', array() );

		/*
		 * When only failures have occurred, an email should only be sent if there are unique failures.
		 * A failure is considered unique if an email has not been sent for an update attempt failure
		 * to a plugin or theme with the same new_version.
		 */
		if ( 'fail' === $type ) {
			foreach ( $failed_updates as $update_type => $failures ) {
				foreach ( $failures as $failed_update ) {
					if ( ! isset( $past_failure_emails[ $failed_update->item->{$update_type} ] ) ) {
						$unique_failures = true;
						continue;
					}

					// Check that the failure represents a new failure based on the new_version.
					if ( version_compare( $past_failure_emails[ $failed_update->item->{$update_type} ], $failed_update->item->new_version, '<' ) ) {
						$unique_failures = true;
					}
				}
			}

			if ( ! $unique_failures ) {
				return;
			}
		}

		$body               = array();
		$successful_plugins = ( ! empty( $successful_updates['plugin'] ) );
		$successful_themes  = ( ! empty( $successful_updates['theme'] ) );
		$failed_plugins     = ( ! empty( $failed_updates['plugin'] ) );
		$failed_themes      = ( ! empty( $failed_updates['theme'] ) );

		switch ( $type ) {
			case 'success':
				if ( $successful_plugins && $successful_themes ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins and themes have automatically updated' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Some plugins and themes have automatically updated to their latest versions on your site at %s. No further action is needed on your part.' ),
						home_url()
					);
				} elseif ( $successful_plugins ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins were automatically updated' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Some plugins have automatically updated to their latest versions on your site at %s. No further action is needed on your part.' ),
						home_url()
					);
				} else {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some themes were automatically updated' );
					$body[]  = sprintf(