diff --git a/inc/events-controllers/class_bento_email_handler.php b/inc/events-controllers/class_bento_email_handler.php
index 3e91eb2..e6662fc 100644
--- a/inc/events-controllers/class_bento_email_handler.php
+++ b/inc/events-controllers/class_bento_email_handler.php
@@ -158,7 +158,14 @@ public function process_email_queue() {
      */
     private function create_email_hash($email_data) {
         // Convert recipient(s) to a consistent format
-        $to = is_array($email_data['to']) ? implode(',', $email_data['to']) : $email_data['to'];
+        $normalized = $this->normalize_recipients($email_data['to'] ?? []);
+        if (!empty($normalized)) {
+            $to = implode(',', $normalized);
+        } else {
+            $to = is_array($email_data['to'] ?? null)
+                ? implode(',', $email_data['to'])
+                : ($email_data['to'] ?? '');
+        }
 
         // Combine key elements of the email
         $hash_input = $to . '|' .
@@ -179,6 +186,18 @@ private function send_via_bento($email_data) {
         $bento_secret_key = $options['bento_secret_key'] ?? '';
         $from_email = $options['bento_from_email'] ?? get_option('admin_email');
         $transactional_override = !empty($options['bento_transactional_override']) && $options['bento_transactional_override'] === '1';
+        $reply_to_enabled = !isset($options['bento_enable_reply_to']) || $options['bento_enable_reply_to'] !== '0';
+
+        $recipients = $this->normalize_recipients($email_data['to'] ?? []);
+        if (empty($recipients)) {
+            Bento_Logger::log('Bento Email Handler: No valid recipients found');
+            return false;
+        }
+
+        $recipient_list = implode(', ', $recipients);
+
+        $parsed_headers = $this->parse_headers($email_data['headers'] ?? []);
+        $reply_to = $this->parse_reply_to($parsed_headers);
 
 
         Bento_Logger::log('Bento Email Handler: Sending via API');
@@ -199,7 +218,7 @@ private function send_via_bento($email_data) {
         $body = array(
             'emails' => array(
                 array(
-                    'to' => $email_data['to'],
+                    'to' => $recipient_list,
                     'from' => $from_email,
                     'subject' => $email_data['subject'],
                     'html_body' => $email_data['message'],
@@ -208,6 +227,10 @@ private function send_via_bento($email_data) {
             )
         );
 
+        if ($reply_to_enabled && !empty($reply_to)) {
+            $body['emails'][0]['reply_to'] = $reply_to;
+        }
+
         Bento_Logger::log('Request body: ' . print_r($body, true));
 
         // Get plugin version
@@ -249,4 +272,125 @@ private function send_via_bento($email_data) {
 
         return true;
     }
-}
\ No newline at end of file
+
+    /**
+     * Parse email headers into a name/value array.
+     */
+    private function parse_headers($headers) {
+        if (empty($headers)) {
+            return [];
+        }
+
+        if (is_string($headers)) {
+            $headers = explode("\n", str_replace("\r\n", "\n", $headers));
+        }
+
+        if (!is_array($headers)) {
+            return [];
+        }
+
+        $parsed = [];
+
+        foreach ($headers as $header) {
+            if (!is_string($header) || trim($header) === '') {
+                continue;
+            }
+
+            if (strpos($header, ':') === false) {
+                continue;
+            }
+
+            [$name, $value] = explode(':', $header, 2);
+            $parsed[strtolower(trim($name))] = trim($value);
+        }
+
+        return $parsed;
+    }
+
+    /**
+     * Extract and validate reply-to address from parsed headers.
+     */
+    private function parse_reply_to($headers) {
+        $value = $headers['reply-to'] ?? null;
+        if (empty($value)) {
+            return null;
+        }
+
+        $candidates = preg_split('/[,;]/', $value);
+        if ($candidates === false) {
+            $candidates = [$value];
+        }
+
+        foreach ($candidates as $candidate) {
+            $candidate = trim($candidate);
+            if ($candidate === '') {
+                continue;
+            }
+
+            if (preg_match('/<([^>]+)>/', $candidate, $matches)) {
+                $email = trim($matches[1]);
+            } else {
+                $email = $candidate;
+            }
+
+            if ($this->is_valid_email($email)) {
+                return $email;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Normalize recipient list into valid email addresses.
+     */
+    private function normalize_recipients($recipients) {
+        if (empty($recipients)) {
+            return [];
+        }
+
+        if (is_string($recipients)) {
+            $recipients = preg_split('/[,;]/', $recipients);
+        }
+
+        if (!is_array($recipients)) {
+            $recipients = (array) $recipients;
+        }
+
+        $normalized = [];
+
+        foreach ($recipients as $recipient) {
+            if (!is_string($recipient)) {
+                continue;
+            }
+
+            $recipient = trim($recipient);
+            if ($recipient === '') {
+                continue;
+            }
+
+            if (preg_match('/<([^>]+)>/', $recipient, $matches)) {
+                $email = trim($matches[1]);
+            } else {
+                $email = $recipient;
+            }
+
+            if ($this->is_valid_email($email)) {
+                $normalized[] = $email;
+            }
+        }
+
+        return array_values(array_unique($normalized));
+    }
+
+    /**
+     * Validate email address using WordPress helpers when available.
+     */
+    private function is_valid_email($email) {
+        if (function_exists('is_email')) {
+            return is_email($email);
+        }
+
+        return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
+    }
+}
diff --git a/tests/Unit/BentoEmailHandlerTest.php b/tests/Unit/BentoEmailHandlerTest.php
index 749e73b..8267d20 100644
--- a/tests/Unit/BentoEmailHandlerTest.php
+++ b/tests/Unit/BentoEmailHandlerTest.php
@@ -114,3 +114,130 @@
     $queue = get_option('bento_email_queue', []);
     expect($queue)->toBe([]);
 });
+
+test('Bento email handler forwards reply-to headers', function () {
+    update_option('bento_settings', [
+        'bento_enable_transactional' => '1',
+        'bento_site_key' => 'site',
+        'bento_publishable_key' => 'pub',
+        'bento_secret_key' => 'sec',
+        'bento_enable_reply_to' => '1',
+    ]);
+
+    $handler = new Bento_Email_Handler();
+
+    $email = [
+        'to' => 'reply@example.com',
+        'subject' => 'Subject',
+        'message' => 'Body',
+        'headers' => ['Reply-To: reply@example.com'],
+    ];
+
+    update_option('bento_email_queue', [[
+        'email_data' => $email,
+        'timestamp' => time(),
+        'hash' => md5('reply@example.com|Subject'),
+    ]]);
+
+    $handler->process_email_queue();
+
+    global $__wp_test_state;
+    $payload = json_decode($__wp_test_state['remote_posts'][0]['args']['body'], true);
+
+    expect($payload['emails'][0]['reply_to'])->toBe('reply@example.com');
+});
+
+test('Bento email handler skips invalid reply-to headers', function () {
+    update_option('bento_settings', [
+        'bento_enable_transactional' => '1',
+        'bento_site_key' => 'site',
+        'bento_publishable_key' => 'pub',
+        'bento_secret_key' => 'sec',
+        'bento_enable_reply_to' => '1',
+    ]);
+
+    $handler = new Bento_Email_Handler();
+
+    $email = [
+        'to' => 'reply@example.com',
+        'subject' => 'Subject',
+        'message' => 'Body',
+        'headers' => ['Reply-To: not-an-email'],
+    ];
+
+    update_option('bento_email_queue', [[
+        'email_data' => $email,
+        'timestamp' => time(),
+        'hash' => md5('reply@example.com|Subject'),
+    ]]);
+
+    $handler->process_email_queue();
+
+    global $__wp_test_state;
+    $payload = json_decode($__wp_test_state['remote_posts'][0]['args']['body'], true);
+
+    expect($payload['emails'][0])->not->toHaveKey('reply_to');
+});
+
+test('Bento email handler normalizes recipient list', function () {
+    update_option('bento_settings', [
+        'bento_enable_transactional' => '1',
+        'bento_site_key' => 'site',
+        'bento_publishable_key' => 'pub',
+        'bento_secret_key' => 'sec',
+    ]);
+
+    $handler = new Bento_Email_Handler();
+
+    $email = [
+        'to' => 'Jane Doe <jane@example.com>, invalid, john@example.com',
+        'subject' => 'Subject',
+        'message' => 'Body',
+        'headers' => [],
+    ];
+
+    update_option('bento_email_queue', [[
+        'email_data' => $email,
+        'timestamp' => time(),
+        'hash' => md5('jane@example.com,john@example.com|Subject'),
+    ]]);
+
+    $handler->process_email_queue();
+
+    global $__wp_test_state;
+    $payload = json_decode($__wp_test_state['remote_posts'][0]['args']['body'], true);
+
+    expect($payload['emails'][0]['to'])->toBe('jane@example.com, john@example.com');
+});
+
+test('Bento email handler accepts case-insensitive reply-to headers', function () {
+    update_option('bento_settings', [
+        'bento_enable_transactional' => '1',
+        'bento_site_key' => 'site',
+        'bento_publishable_key' => 'pub',
+        'bento_secret_key' => 'sec',
+        'bento_enable_reply_to' => '1',
+    ]);
+
+    $handler = new Bento_Email_Handler();
+
+    $email = [
+        'to' => 'reply@example.com',
+        'subject' => 'Subject',
+        'message' => 'Body',
+        'headers' => ['REPLY-TO: reply@example.com'],
+    ];
+
+    update_option('bento_email_queue', [[
+        'email_data' => $email,
+        'timestamp' => time(),
+        'hash' => md5('reply@example.com|Subject'),
+    ]]);
+
+    $handler->process_email_queue();
+
+    global $__wp_test_state;
+    $payload = json_decode($__wp_test_state['remote_posts'][0]['args']['body'], true);
+
+    expect($payload['emails'][0]['reply_to'])->toBe('reply@example.com');
+});