> For the complete documentation index, see [llms.txt](https://islamu.gitbook.io/islamu-event/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://islamu.gitbook.io/islamu-event/documentation/readme/communications-and-notifications/listmonk.md).

# Listmonk

Synchronize registration subscribers to an optional external Listmonk instance.

The Listmonk integration synchronizes eligible attendee registration subscribers into configured mailing lists within a self-hosted [Listmonk](https://listmonk.app) newsletter server. It is strictly an opt-in outbound subscriber synchronization bridge, not the primary notification store or [Email SMTP](/islamu-event/documentation/readme/communications-and-notifications/email-smtp.md) dispatch worker.

***

## 1. Configuration & Secret Binding

Operators configure Listmonk parameters via [Environment Variables](/islamu-event/documentation/readme/configuration-and-operations/environment-variables.md#listmonk-newsletter--subscriber-sync):

| Setting                             | Purpose                                                                                                                          |
| ----------------------------------- | -------------------------------------------------------------------------------------------------------------------------------- |
| `LISTMONK_ENABLED`                  | Set `true` to activate the subscriber synchronization worker.                                                                    |
| `LISTMONK_INSTANCE_URL`             | Base URL of the external Listmonk instance (e.g. `https://newsletter.example.org`).                                              |
| `LISTMONK_DEFAULT_LIST_ID`          | Numerical ID of the default attendee mailing list in Listmonk.                                                                   |
| `LISTMONK_PRECONFIRM_SUBSCRIPTIONS` | Set `true` if opt-in consent is pre-verified during event checkout.                                                              |
| `LISTMONK_SYNC_ON_REGISTRATION`     | Automatically sync subscriber details upon successful ticket registration.                                                       |
| `LISTMONK_API_USERNAME`             | Listmonk API username.                                                                                                           |
| `LISTMONK_API_KEY`                  | Listmonk API token (bound via [Secrets Management](/islamu-event/documentation/readme/configuration-and-operations/secrets.md)). |

***

## 2. Synchronization & Dead-Letter Recovery

* **Asynchronous Processing**: Attendee synchronization executes in the background without blocking ticket checkout latency.
* **Health Probes**: The worker registers a dedicated readiness check at `/health` to verify connectivity to the Listmonk API without echoing authentication tokens (see [Health Check Endpoints](/islamu-event/documentation/readme/configuration-and-operations/troubleshooting-and-health.md#health-check-endpoints-reference)).
* **Dead-Letter Handling**: If Listmonk is temporarily unreachable, sync tasks enter a bounded retry queue with exponential backoff before landing in dead-letter storage for manual operator review.

***

## 3. Privacy & Consent Governance

Enabling Listmonk does not automatically subscribe all users. The platform requires explicit attendee consent during event checkout. When an attendee exercises their Right-to-Erasure, the outbox automatically triggers a deletion request to Listmonk to scrub their email address (see [Privacy Erasure & GDPR Compliance](/islamu-event/documentation/readme/security-and-identity/privacy-erasure.md)).

***

## Related Guides & Next Steps

* [**Email SMTP Delivery**](/islamu-event/documentation/readme/communications-and-notifications/email-smtp.md) — Configure transactional ticket delivery emails.
* [**In-App Notifications**](/islamu-event/documentation/readme/communications-and-notifications/in-app-notifications.md) — Authoritative platform inbox for user alerts.
* [**Environment Variables Reference**](/islamu-event/documentation/readme/configuration-and-operations/environment-variables.md#listmonk-newsletter--subscriber-sync) — Full reference for Listmonk environment settings.
* [**Privacy Erasure & GDPR**](/islamu-event/documentation/readme/security-and-identity/privacy-erasure.md) — Learn how external newsletter subscribers are handled during account deletion.


---

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