Hello, Sorry for my reply. I am only an F-Secure user (their home solutions). Sounds that Lithium-platform (Community forum) with related functionality already. For example, when you read private letter - there should be visible button like "Ignore". As a result, (user?!) can be added to "Ignore list" (such list is also visible under private letters board). In addition, there is an ability to disable entire "pm" functionality (does not receive anything from anyone). And an ability to use "Friends" list. Could you explain whether something of such things are about your concern? Or your request is about something else? Sorry for my English! Thanks!