When post.jar is used with a custom URL (e.g. for multi-core), it silently ignores -Dparams flag and requires parameters to be appended directly to -Durl value.
The problem is the following code:
String params = System.getProperty("params", "");
urlStr = System.getProperty("url", SimplePostTool.appendParam(DEFAULT_POST_URL, params));
The workaround exists (by using -Durl="http://customurl?param1=value¶m2=value"), but it is both undocumented as a special case and clunky as Url and params may be coming from different places. It would be good to have this consistent.