---
title: "Queued notifications"
manual: "Laravel-style Notification System - Slack Channel"
version: "1.0"
permalink: "https://docs.typo3.org/permalink/agencelex/notifications-slack:slack-queued-notifications@1.0"
source: "Usage/QueuedNotifications.rst"
rendered: "2026-10-16T12:40:55+00:00"
---

# Queued notifications {#slack-queued-notifications}

The parent `agencelex/notifications` extension integrates with Symfony
Messenger. Slack uses that existing delivery mechanism and does **not**
register a separate queue transport.

## Mark a notification for queued delivery {#mark-a-notification-for-queued-delivery}

```php
<?php

declare(strict_types=1);

use Illuminate\Contracts\Queue\ShouldQueue;
use Lex\Notifications\Notification;
use Lex\Notifications\Slack\Message\SlackMessage;

final class ImportFinished extends Notification implements ShouldQueue
{
    public function via(object $notifiable): array
    {
        return ['slack'];
    }

    public function toSlack(object $notifiable): SlackMessage
    {
        return SlackMessage::text('Nightly import completed.');
    }
}

$manager->route('slack', 'webhook:monitoring')
    ->notify(new ImportFinished());
```

`ShouldQueue` is provided by the notification core's queue contract
(depending on your installation, the resolved interface belongs to
`illuminate/contracts`). Use the version supplied by the core.

> [!IMPORTANT]
> TYPO3 can route Messenger messages to a synchronous transport by
> default. Declaring `ShouldQueue` does **not** guarantee that
> messages will be processed in the background. Configure an asynchronous
> Messenger transport and workers through the notification core for
> truly deferred delivery.

## Why named webhooks matter {#why-named-webhooks-matter}

The `SlackRoute::webhookNamed('monitoring')` value contains only an
alias. Its secret URL is looked up in TYPO3 configuration during the
send operation, including when a worker later processes the message.

By contrast, `SlackRoute::webhook($url)` contains the full secret URL;
serialization into an asynchronous queue may expose that URL to anyone
who can inspect the queue storage.

## Retries and duplicates {#retries-and-duplicates}

SlackTransport never automatically resends a message. It throws an
exception on HTTP and Slack application errors, with information about
whether an error appears retryable.

Slack rate limits may include `Retry-After`. That value is exposed as
`SlackTransportException::retryAfterSeconds`, but the channel does
not configure Messenger retries or automatically enforce the delay.

A timeout or server failure leaves the actual delivery outcome
uncertain. Retrying could post a duplicate. Configure retries according
to your operational tolerance and monitor the failure transport/worker
logs of the notification core.

Next: [Error handling](https://docs.typo3.org/permalink/agencelex/notifications-slack:slack-errors@1.0) and
[Security](https://docs.typo3.org/permalink/agencelex/notifications-slack:slack-security@1.0).