feat: add simple smtp plugin

Author: gabe565

Dockerfile

@@ -47,3 +47,5 @@ ARG PHP_EXTENSIONS
 RUN --mount=type=bind,from=ext-installer,src=/usr/bin/install-php-extensions,dst=/usr/bin/install-php-extensions <<EOT
   install-php-extensions $PHP_EXTENSIONS
 EOT
+
+COPY --chown=www-data:www-data wp-content /usr/src/wordpress/wp-content

wp-content/mu-plugins/smtp.php

@@ -0,0 +1,39 @@
+<?php
+
+if (!defined('ABSPATH')) {
+  exit;
+}
+
+add_action('phpmailer_init', 'phpmailer_envconfig');
+
+function phpmailer_envconfig($phpmailer) {
+  $mailer = getenv_docker('MAIL_MAILER', '');
+
+  if ($mailer === 'smtp') {
+    $phpmailer->isSMTP();
+    $phpmailer->Host       = getenv_docker('MAIL_HOST', '');
+    $phpmailer->Port       = getenv_docker('MAIL_PORT', 587);
+    $phpmailer->SMTPSecure = getenv_docker('MAIL_SMTP_SECURE', 'tls');
+    $phpmailer->SMTPAuth   = getenv_docker('MAIL_SMTP_AUTH', true);
+    $phpmailer->Username   = getenv_docker('MAIL_USERNAME', '');
+    $phpmailer->Password   = getenv_docker('MAIL_PASSWORD', '');
+
+    $from = getenv_docker('MAIL_FROM_ADDRESS', '');
+    if ($from) {
+      $phpmailer->From = $from;
+    }
+
+    $fromName = getenv_docker('MAIL_FROM_NAME', '');
+    if ($fromName) {
+      $phpmailer->FromName = getenv_docker('MAIL_FROM_NAME', '');
+    }
+  }
+}
+
+add_action('wp_mail_failed', 'phpmailer_error_log');
+
+function phpmailer_error_log($wp_error) {
+  if (WP_DEBUG) {
+    error_log('Mail failed: ' . $wp_error->get_error_message());
+  }
+};