appendACLExpression(str, CONVERSATION_ID, msg.getConversationId());
Properties userDefProps = msg.getAllUserDefinedParameters();
if (userDefProps != null) {
Enumeration e = userDefProps.propertyNames();
while (e.hasMoreElements()) {
String key = ((String)e.nextElement());
if (key.indexOf(' ') == -1) {
if ( (!key.startsWith("X-")) && (!key.startsWith("x-")) )
appendACLExpression(str, ":X-"+key, userDefProps.getProperty(key));