Title: Lettr – Email API Author: vojtechj Published: 19 de Mayo de 2026 Last modified: 11 de Septiembre de 2026 --- Buscar plugins ![](https://s.w.org/plugins/geopattern-icon/lettr.svg) # Lettr – Email API Por [vojtechj](https://profiles.wordpress.org/vojtechj/) [Descargar](https://downloads.wordpress.org/plugin/lettr.1.4.0.zip) * [Detalles](https://cl.wordpress.org/plugins/lettr/#description) * [Reseñas](https://cl.wordpress.org/plugins/lettr/#reviews) * [Instalación](https://cl.wordpress.org/plugins/lettr/#installation) * [Desarrollo](https://cl.wordpress.org/plugins/lettr/#developers) [Soporte](https://wordpress.org/support/plugin/lettr/) ## Descripción Send transactional and marketing emails from your WordPress site using the [Lettr](https://lettr.com) email API. Lettr replaces the default WordPress email system with a reliable, developer- friendly API that delivers emails to inboxes — not spam folders. #### Why Lettr? * **Reliable email delivery** — Built on battle-tested infrastructure with SPF, DKIM, and DMARC authentication out of the box. * **Simple setup** — Connect your WordPress site with a single API key. No SMTP configuration needed. * **Transactional email at scale** — Send password resets, order confirmations, notifications, and more through the Lettr email API. * **Real-time tracking** — Monitor opens, clicks, bounces, and deliverability from the Lettr dashboard. * **Templates & personalization** — Use the Lettr drag-and-drop editor and merge tags for dynamic content. * **Developer-first** — RESTful API, detailed documentation, and SDKs for PHP, Node.js, Python, Go, Rust, Java, and Laravel. #### How it works This plugin overrides the default WordPress `wp_mail()` function and routes all outgoing emails through the Lettr API. This means every email your site sends — including emails from WooCommerce, contact form plugins, and any other plugin — is delivered through Lettr automatically. #### Links * [Lettr Website](https://lettr.com) * [Documentation](https://docs.lettr.com) * [API Reference](https://docs.lettr.com/api-reference/introduction) ### External services This plugin connects to the Lettr API at `app.lettr.com` to deliver email on behalf of your WordPress site. Each time `wp_mail()` is invoked, the plugin sends the following data to Lettr over HTTPS so that Lettr can process and deliver the message: * The configured sender email address and name * Recipient, CC, BCC, and Reply-To addresses * The email subject, HTML and/or plain text body, and any attachments * Any custom email headers, tags, or metadata supplied by the calling code * Your Lettr API key (sent as a Bearer token in the `Authorization` header for authentication) The plugin also calls `app.lettr.com/api/auth/check` to validate the API key when you save it on the settings screen. This service is provided by Lettr. By using this plugin you agree to Lettr’s terms and acknowledge their privacy practices: * Terms of Service: [https://lettr.com/terms](https://lettr.com/terms) * Privacy Policy: [https://lettr.com/privacy-policy](https://lettr.com/privacy-policy) ## Instalación 1. Upload the plugin to `/wp-content/plugins/lettr` or install via the WordPress plugin installer. 2. Activate the plugin through the **Plugins** menu. 3. Go to **Settings Lettr** and enter your API key from the [Lettr dashboard](https://lettr.com). 4. Configure your sender name and email address. 5. Send a test email to verify everything is working. ## FAQ ### Do I need a Lettr account? Yes. Sign up for free at [lettr.com](https://lettr.com) to get your API key. ### Does this work with WooCommerce? Yes. Lettr handles all emails sent via the standard WordPress `wp_mail()` function, which includes WooCommerce order confirmations, shipping notifications, and customer emails. ### Do I need to configure SMTP? No. Lettr uses a REST API instead of SMTP, which means there are no ports to open or SMTP credentials to manage. ### Where can I find my API key? Log in to your account at [lettr.com](https://lettr.com) and navigate to the API Keys section. ## Reseñas No hay reseñas para este plugin. ## Colaboradores & Desarrolladores “Lettr – Email API” es software de código abierto. Las siguientes personas han contribuido a este plugin. Colaboradores * [ vojtechj ](https://profiles.wordpress.org/vojtechj/) [Traduce “Lettr – Email API” a tu idioma.](https://translate.wordpress.org/projects/wp-plugins/lettr) ### ¿Interesado en el desarrollo? [Revisa el código](https://plugins.trac.wordpress.org/browser/lettr/), echa un vistazo al [repositorio SVN](https://plugins.svn.wordpress.org/lettr/), o suscríbete al [registro de desarrollo](https://plugins.trac.wordpress.org/log/lettr/) por [RSS](https://plugins.trac.wordpress.org/log/lettr/?limit=100&mode=stop_on_copy&format=rss). ## Historial de cambios #### 1.4.0 * Add `list_folders()` — the folders templates are filed into, with each folder’s purpose and template count. Nothing else in the API returns a folder id, so without it a caller either omits `folder_id` and accepts whichever folder the API picks, or hardcodes an integer read out of an app URL. * `create_template()` accepts `purpose` (`transactional` or `campaign`), and `list_templates()` accepts `purpose` and `folder_id` filters. A campaign can only send a template whose purpose is `campaign`, and the purpose cannot be changed after creation. * Add the `lettr_idempotency_key` filter. Return a stable string and a retried ` wp_mail()` replays the original send instead of delivering a second email. Opt- in by design: deriving a key from the payload would silently collapse two legitimately identical notifications into one. `Lettr_Api::send_email()` also takes the key as a second argument. * Template responses now carry `preparation_status` (`pending`, `ready`, `failed`)— documented; no client change was needed, since responses pass through decoded. #### 1.3.0 * Add bulk topic subscription API client methods (`bulk_subscribe_audience_contacts_to_topics`,` bulk_unsubscribe_audience_contacts_from_topics`). * `bulk_create_audience_contacts()` now documents the per-contact `contacts` request shape, the batch-wide `list_ids` / `topics` / `update_existing` options, and the `updated` / `error_count` / `errors` / `contacts` response fields. No call signature changed — existing payloads send exactly as before. * **Behaviour change from the Lettr API:** creating a contact whose email already exists now returns HTTP 409, so `create_audience_contact()` fails with a `WP_Error` code of `lettr_api_resource_already_exists` (status 409). It previously returned HTTP 500, i.e. `lettr_api_send_error` (status 500). Custom code branching on the old code no longer matches, and a 409 here must not be retried. #### 1.2.0 * Add campaigns API client methods (list, show, events, send, schedule, unschedule). #### 1.1.0 * Add audience API client methods (lists, contacts, topics, properties, segments). * Bump tested-up-to to WordPress 7.0. #### 1.0.0 * Initial release. ## Meta * Versión **1.4.0** * Última actualización **hace 1 semana** * Instalaciones activas **Menos de 10** * Versión de WordPress ** 5.8 o superior ** * Probado hasta **7.0.5** * Versión de PHP ** 7.2 o superior ** * Idioma * [English (US)](https://wordpress.org/plugins/lettr/) * Etiquetas * [email](https://cl.wordpress.org/plugins/tags/email/)[Email API](https://cl.wordpress.org/plugins/tags/email-api/) [smtp](https://cl.wordpress.org/plugins/tags/smtp/)[transactional email](https://cl.wordpress.org/plugins/tags/transactional-email/) * [Vista Avanzada](https://cl.wordpress.org/plugins/lettr/advanced/) ## Calificaciones Aún no se han enviado valoraciones. [Tu reseña](https://wordpress.org/support/plugin/lettr/reviews/#new-post) [Ver todas las reseñas](https://wordpress.org/support/plugin/lettr/reviews/) ## Colaboradores * [ vojtechj ](https://profiles.wordpress.org/vojtechj/) ## Soporte ¿Tienes algo que decir? ¿Necesitas ayuda? [Ver el foro de soporte](https://wordpress.org/support/plugin/lettr/)