Automatic bounce and complaint management using Postmark to send MailPoet (and other) emails

postmark-webhooks.php

add_action( 'admin_post_nopriv_process_postmark_events', 'bhww_core_postmark_events_webhook' );
/**
 * Add a webhook to enable automated MailPoet bounce (or spam complaint or unsubscribe)
 * handling from Postmark events JSON data
 *
 * Change this webhook URL for each site, and copy/paste into Postmark Webhook URL form:
 * https://[YOUR WEBSITE URL]/wp-admin/admin-post.php?action=process_postmark_events
 *
 * Make sure there is not an admin redirect active,
 * or if there is, modify it to allow webhook access
 *
 * Give credit where credit is due:
 * @link https://bhanusingh.in/creating-a-custom-webhook-in-wordpress-to-get-data-from-third-part-services
 * @link https://developer.wordpress.org/reference/hooks/admin_post_nopriv_action/
 *
 * @since 2022/12/12
 */
function bhww_core_postmark_events_webhook() {

	$email = '';
	$type  = '';

	// Get data from the webhoook
	$request = file_get_contents( 'php://input' );

	// Decode the JSON data
	$json_data = json_decode( $request, true );

	if ( ! empty( $json_data ) ) {

		if ( ! empty( $json_data['Email'] ) ) {
			$email = $json_data['Email'];
		} else {
			$email = $json_data['Recipient']; // Subscription Change
		}

		if ( ! empty( $json_data['Type'] ) ) {
			$type = $json_data['Type'];
		} else {
			$type = $json_data['RecordType']; // Subscription Change
		}

	}

	// log it in /wp-content/debug.log
	// WP_DEBUG and WP_DEBUG_LOG need to be set to 'true' in wp-config.php for this to work
  	error_log( print_r( $json_data, true ) );

	// Notification email information
  	$site    = '[YOUR WEBSITE URL]'; // Change to match website URL
  	$to      = '[YOUR EMAIL ADDRESS]'; // This is where the email will be sent
	$headers = array( 'Content-Type: text/html; charset=UTF-8' );

    // These event types come from Postmark
	$event_types = array( 'HardBounce', 'SpamComplaint', 'SubscriptionChange' );

	if ( in_array( $type, $event_types ) ) {

		if ( $type === 'HardBounce' ) {

			error_log( 'This email bounced' );

			$status  = 'bounced';
			$subject = 'Postmark bounce - ' . $site;
			$body    = 'The email address ' . $email . ' just bounced on ' . $site;

		} elseif ( $type === 'SpamComplaint' ) {

			error_log( 'This user marked us as spam!!!' );

			$status  = 'unsubscribed';
			$subject = 'Postmark spam complaint - ' . $site;
			$body    = 'The email address ' . $email . ' just marked us as spam on ' . $site;

		} elseif ( $type === 'SubscriptionChange' ) {

			error_log( 'This user unsubscribed' );

			$status  = 'unsubscribed';
			$subject = 'Postmark unsubscribe - ' . $site;
			$body    = 'The email address ' . $email . ' just unsubscribed on ' . $site;

		}

		// Send an email to yourself about this event
		wp_mail( $to, $subject, $body, $headers );

		// Check to see if MailPoet plugin is active
		if ( is_plugin_active( 'mailpoet/mailpoet.php' ) ) {

			// Update the subscriber in MailPoet
			global $wpdb; // Need this!

			$table = $wpdb->prefix . 'mailpoet_subscribers';

			// The new data value
			$data = array(
				'status' => $status,
			);

			// If these conditions are met
			$where = array(
				'email'  => $email,
				'status' => 'subscribed',
			);

			// Update the subscriber's status in the database
			$wpdb->update( $table, $data, $where );

		}

	}

}