Sued through the mail...

I moved about 2 months ago and am wondering...can a CA sue me through the mail? I'm working with them through a dmp but I read about how some will try and get default judgements even though you use a DMP. I live in Pennsylvania if that helps. It took the post office forever to process my address change and i haven't gotten mail from that old address in like 6 weeks. Basicly i want to know if there's any chance there's regular mail sitting there waiting for me. Do you need to be served with those kinds of things?