Our DNS provider (our network operations center) is having an occasional problem with RBL requests periodically getting log-jammed.  From what we can figure at this point, one or more RBL's either becomes non-responsive, or the total number of requests from our DNS provider hits some kind of limit for one or more RBL's.  At that point, all request timings across the board start to balloon from milliseconds to (in some cases) several minutes or more.

 

Would it be possible (or even advisable) to add another option to each RBL setup, that when the response time exceeds an editable number of ms, then additional requests are ignored and the message is processed without that RBL?