diff --git a/snappymail/v/0.0.0/app/libraries/snappymail/sasl/login.php b/snappymail/v/0.0.0/app/libraries/snappymail/sasl/login.php
index 9dcbd446d..52608a49f 100644
--- a/snappymail/v/0.0.0/app/libraries/snappymail/sasl/login.php
+++ b/snappymail/v/0.0.0/app/libraries/snappymail/sasl/login.php
@@ -11,9 +11,8 @@ class Login extends \SnappyMail\SASL
 	{
 		// $challenge should be 'VXNlcm5hbWU6', but broken on some systems
 		// See https://github.com/the-djmaze/snappymail/issues/693
-		if ($challenge && \str_starts_with($this->decode($challenge), 'Username:')) {
-//		if ($challenge && 'Username:' !== $this->decode($challenge)) {
-			throw new \Exception("Invalid response: {$challenge}");
+		if ($challenge && !\str_starts_with($this->decode($challenge), 'Username:')) {
+			throw new \Exception("Invalid response: {$this->decode($challenge)}");
 		}
 		$this->passphrase = $passphrase;
 		return $this->encode($username);
diff --git a/test/sasl.php b/test/sasl.php
new file mode 100644
index 000000000..f36d238e4
--- /dev/null
+++ b/test/sasl.php
@@ -0,0 +1,25 @@
+<?php
+//$_ENV['SNAPPYMAIL_INCLUDE_AS_API'] = true;
+//require '../index.php';
+
+define('SNAPPYMAIL_LIBRARIES_PATH', dirname(__DIR__) . '/snappymail/v/0.0.0/app/libraries');
+if (false === set_include_path(SNAPPYMAIL_LIBRARIES_PATH . PATH_SEPARATOR . get_include_path())) {
+	exit('set_include_path() failed. Probably due to Apache config using php_admin_value instead of php_value');
+}
+spl_autoload_extensions('.php');
+/** lowercase autoloader */
+spl_autoload_register();
+/** case-sensitive autoloader */
+spl_autoload_register(function($sClassName){
+	$file = SNAPPYMAIL_LIBRARIES_PATH . strtr($sClassName, '\\', DIRECTORY_SEPARATOR) . '.php';
+//		if ($file = stream_resolve_include_path(strtr($sClassName, '\\', DIRECTORY_SEPARATOR) . '.php')) {
+	if (is_file($file)) {
+		include_once $file;
+	}
+});
+
+$LOGIN = new \SnappyMail\SASL\Login;
+$LOGIN->base64 = true;
+var_dump($LOGIN->authenticate('john', 'doe', 'VXNlcm5hbWU6'));
+var_dump($LOGIN->authenticate('john', 'doe', 'VXNlcm5hbWU6CG'));
+var_dump($LOGIN->authenticate('john', 'doe', 'UGFzc3dvcmQ6'));