Could any one explain "No Auto-Reply to this Domain" in inbound mail creation

Hi ,
I just what to know at inbound mail creation there is option called No Auto-Reply to this Domainso may i know what is functionality of this option ,is this for auto case creation .

I went through the docs,what i think
If add (or should I add please clarify on it also) if any incoming mail comes with this id auto case creation won’t happen ,am I correct on it ? If i am wrong please correct me ?