FL Statute 48.031 Allows for a witness subpoena to be mailed in misdemeanor and felony cases but, unless it is sent certified mail and signed for, may not be used as the basis for a contempt charge. The subpoena must be mailed 7 days prior to the hearing. Service of a subpoena may also be posted 5 days prior to the hearing, if there have been three separate attempts at service at different times of the day or night. Please consult a local Criminal Defense attorney to discuss the specifics of your case in greater detail. Good luck.