From my understanding you need to make every attempt to notify him, so if you have already sent certified mail then you should get the Sheriff to serve him and if that fails put a add in the paper for a couple of days, keep all documents of failed attempts and if all failed go and get put on a docket for a court date.
I have a questions. I filed an absolute divorce and had the papers sent to my ex certified mail. He did not make it to pick them up so they were sent back to me. Will this still work when going for my court date??