I agree. This is not that impossible. What if the process server yells at her with a bullhorn from 25 feet away, “Hillary Clinton, you’ve been served” and then tosses the paper in her direction, would not that count?
I think there is a requirement that the papers actually get into the hands of the target or their representative. If the papers are mailed, she can say she never received them. Its best to pay your local sheriff to do the dirty work for you.
Yelling at her with a bullhorn and then tossing something in her direction is a damned good way to spook her Secret Service protection and get yourself shot. I would advise a against it.