When a document has been e-filed, it is served on all participating parties and marked FILED with the Nassau County Clerk's Office. Delivering legal papers is called "service of process".The law says that legal papers have to be "served" (delivered) the right way. To update your personal information, including your primary service email address, log into NYSCEF and choose "Account Settings" on the left menu. Submit the legal documents you want served and basic service information. Auto-fill and address verification make it fast and easy. Complete your questionnaire online, you may also complete your Questionnaire using the telephone service at 1-866-648-4880. Don't forget to bring it with you! What are the address and hours of the Nassau County Clerk's Office? The Nassau County Clerk's Office is located at 240 Old Country Road, Mineola.