Scalability and support with Privacy List


We have just made available our latest free web service to use XMPP for backend message routing. If you are interested, feel free to visit and give us feedback.

Per my understanding of XMPP spec, user (or server ??) can select privacy policy such that only the designated sender(s) can send messages to the user. All others will be blocked (or messages dropped) by the server. My questions are:

(1) has anyone had experience implementing this policy and where should one go in setting up such list under Wildfire 3.0?

(2) if so, how does the server performance got impacted as it needs to inspect the blocking list per sent message)? Does anyone has any experience on the performance hit as related to number of users (or messages) using this service increases?

(3) has anyone had experience in setting the block policy by default and incrementally opened by users as they choose to?

I would like to hear from both developer and administrator’'s perspective. I am experimenting with jabberd and wildfire at this time and thought to ask if anyone has tried this before.