Can divorce papers be left on a doorstep?

My husband filed for divorce. His process server showed up at my apartment when I was not present. My roommate told him he could not take service for me as it was his understanding that in Maryland the divorce papers must be handed to the person who is being served. The process server then got really pissed off and said he was following the other attorney's orders and left the papers on the doorstep and walked away. Is this proper service for a divorce in Maryland? I have not touched the papers yet.