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 4a84b4835..9dcbd446d 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
@@ -9,7 +9,10 @@ class Login extends \SnappyMail\SASL
 
 	public function authenticate(string $username, string $passphrase, ?string $challenge = null) : string
 	{
-		if ($challenge && 'Username:' !== $this->decode($challenge)) {
+		// $challenge should be 'VXNlcm5hbWU6', but broken on some systems
+		// See https://github.com/the-djmaze/snappymail/issues/693
+		if ($challenge && \str_starts_with($this->decode($challenge), 'Username:')) {
+//		if ($challenge && 'Username:' !== $this->decode($challenge)) {
 			throw new \Exception("Invalid response: {$challenge}");
 		}
 		$this->passphrase = $passphrase;
@@ -18,6 +21,7 @@ class Login extends \SnappyMail\SASL
 
 	public function challenge(string $challenge) : ?string
 	{
+		// $challenge should be 'UGFzc3dvcmQ6'
 		if ($challenge && 'Password:' !== $this->decode($challenge)) {
 			throw new \Exception("invalid response: {$challenge}");
 		}