Reciprocity : Always Allow A Reply?

Privacy settings can throw up some anomalous behaviour:

Privacy Settings 

  Content settings

    Messages

          All members/Only my friends can send me messages

    Notes

          All members/Only my friends can view my notes or drop me a note

If someone whose settings are Only my friends sends me a message, I cannot reply to it - unless we are friends. I would have thought that you should be able to send a single reply to a received message - irrespective of the privacy setting of the sender. I imagine that the sender is usually expecting a reply.

You are right!

Its a bit tricky but it seems like the developers of this site has missed this situation.

Certainly challenging to implement. Some classified ads site do it: you place an ad; they hide your address. They send you any responses - but hide the responder's address from you - and allow you a single reply to the enquirer.

The situation here is much tougher, since you're allowed to use their address if you're friends. I'd probably introduce the concept of temporary friend to fix it.