Hello? Oh sheesh "experts" again...Sorry, IMO they are greatly overrated! I forgot already what kind of info is being sent in the letters... in any way, if he is harassing you, this is not legal!
(I won't give my impressions of law enforcement here...but I have experience from the inside.) If there is any intent to do something you wouldn't like, then it is an assault.

IF you sent the legal letter of notification, do NOT contact your stalker again, in any way. They thrive on that, won't take what you say as truth, and will it will look poorly for you in the future.

I applaud your insistance and suggest you find another person to complain to, and do so in writing also. Did you make yourself more safe yet? Often the sheer filing of an "order" against one causes them to "go off the deep end" and you need to be aware (but not scared) and prepared. Have you contacted a lawyer, on the phone at least, for basic advice?