Subpoena was sent by certified mail to my mothers address am I required to go?

My mother did not pick up the letter and did not sign for it because I do not live there and the person who sent the subpoena sent my sister a text telling her about the court date but I was not notified by him or the court. What are the rules for contempt and will the judge still hear the case even though I was not notified of the court date?