[Postfix/Rspamd] Do not reject unauthenticated sender mismatches but rewrite their subject and assign symbol SPOOFED_SENDER with score 1.0

data/conf/rspamd/local.d/metrics.conf

@@ -34,3 +34,7 @@ group "MX" {
 	  one_shot = "true";
 	}
 }
+symbol "SPOOFED_SENDER" {
+	description = "Sender is not authenticated but part of mailcow managed domains";
+	score = 1.0;
+}