Simple Script to run and debug tests for smtp mail on WordPress

test-smtp.php

<?php
  
  /**
   * This is used to test and debug the Bedrock Environment Mailer
   * https://github.com/hackur/bedrock-env-mailer
   *
   * Code is derived from it.
   * License: MIT
   */
  
use PHPMailer\PHPMailer\PHPMailer;
use function Env\env;

require_once __DIR__ . '/wp-config.php';

if ( ! current_user_can( 'manage_options' ) ) {
	// Redirect to home page if not accessed from allowed host
	header( 'HTTP/1.1 302 Moved Permanently' );
	header( 'Location: /' );
	exit();
}

$to      = ! empty( $_POST['to'] ) ? $_POST['to'] : null;
$subject = ! empty( $_POST['subject'] ) ? $_POST['subject'] : 'Test Email from Bedrock Env Mailer Test Script';
$message = ! empty( $_POST['message'] ) ? $_POST['message'] : 'This is a test email sent from the Bedrock Env Mailer plugin.';
?>
<style>
	i { color: grey; }
	strong { color: green; }
	strong i { color: red; }
</style>
<form method="post">
	<label>To:
	<input type="text" name="to" value="<?php echo esc_attr( $to ); ?>"></label><br>
	<label>Subject:
	<input type="text" name="subject" value="<?php echo esc_attr( $subject ); ?>"></label><br>
	<label>Message:<br>
	<textarea name="message" rows="10" cols="50"><?php echo esc_attr( $message ); ?></textarea></label><br>
	<button type="submit">Send Test Email</button>
<pre>
<?php

echo 'TEST ENV MAIL' . PHP_EOL;

// Display current SMTP settings from environment variables
echo 'WP_MAIL_SMTP_USERNAME: ' . ( env( 'WP_MAIL_SMTP_USERNAME' ) ?: '<i>Not Set</i>' ) . PHP_EOL;
echo 'WP_MAIL_SMTP_PASSWORD: ' . ( env( 'WP_MAIL_SMTP_PASSWORD' ) ? '<strong>Set</strong>' : '<strong><i>Not Set</i></strong>' ) . PHP_EOL;
echo 'WP_MAIL_SMTP_HOST: ' . ( env( 'WP_MAIL_SMTP_HOST' ) ?: '<i>Not Set</i>' ) . PHP_EOL;
echo 'WP_MAIL_SMTP_PORT: ' . ( env( 'WP_MAIL_SMTP_PORT' ) ?: '<i>Not Set</i>' ) . PHP_EOL;
echo 'WP_MAIL_SMTP_SECURE: ' . ( env( 'WP_MAIL_SMTP_SECURE' ) ?: '<i>Not Set</i>' ) . PHP_EOL;
echo 'WP_MAIL_SMTP_DEBUG: ' . ( env( 'WP_MAIL_SMTP_DEBUG' ) ?: '<i>Not Set</i>' ) . PHP_EOL;

add_action(
	'wp_mail_failed',
	function ( $wp_error ) {
		echo 'wp_mail_failed: ' . print_r( $wp_error, true ) . PHP_EOL;
	}
);

if ( $_SERVER['REQUEST_METHOD'] === 'POST' ) {
	if ( empty( $to ) ) {
		echo 'Please provide a recipient email address.' . PHP_EOL;
		exit();
	}

	if ( ! filter_var( $to, FILTER_VALIDATE_EMAIL ) ) {
		echo 'Invalid email address format.' . PHP_EOL;
		exit();
	}

	$mail_sent = wp_mail( $to, $subject, $message );

	if ( $mail_sent ) {
		echo 'Email sent successfully.' . PHP_EOL;
	} else {
		echo 'Failed to send email.' . PHP_EOL;

		global $phpmailer;
		if ( isset( $phpmailer ) ) {
			echo 'PHPMailer ErrorInfo: ' . $phpmailer->ErrorInfo . PHP_EOL;
			if ( ! empty( $phpmailer->smtp ) && method_exists( $phpmailer->smtp, 'getLastReply' ) ) {
				echo 'SMTP Last Reply: ' . $phpmailer->smtp->getLastReply() . PHP_EOL;
			}
			if ( ! empty( $phpmailer->Mailer ) ) {
				echo 'Mailer: ' . $phpmailer->Mailer . PHP_EOL;
			}
			if ( ! empty( $phpmailer->Host ) ) {
				echo 'Host: ' . $phpmailer->Host . PHP_EOL;
			}
		}
	}
}