diff --git a/api/src/Mail/Sieve.php b/api/src/Mail/Sieve.php
index 80236465a8..6c5f5b120d 100644
--- a/api/src/Mail/Sieve.php
+++ b/api/src/Mail/Sieve.php
@@ -98,6 +98,11 @@ class Sieve extends Horde\ManageSieve
 				//'logger' => new \admin_mail_logger('/tmp/sieve.log'),
 			);
 		}
+		// try "PLAIN" first, in case IMAP wrongly reports some digest, it does not (correctly) implement
+		if (self::$supportedAuthMethods[0] !== self::AUTH_PLAIN)
+		{
+			array_unshift(self::$supportedAuthMethods, self::AUTH_PLAIN);
+		}
 		parent::__construct($params);
 
 		$this->displayCharset	= Translation::charset();