Per Investopedia:

A valid subpoena should include the following:

• The name of the court issuing the subpoena
• The name, address, and contact details of the attorney who initiated the subpoena
• The names of the parties involved
• The assigned case docket number

If you receive a subpoena, legal experts recommend double-checking the hearing date and time and rearranging your schedule to ensure you will be present, thereby avoiding a stiff penalty for failure to appear. It is also recommended that you know exactly what documents are required to be produced by the subpoena, and ensuring they are kept safe until the hearing.

Note that documents do not only mean paper documents, but also photographs, sound or video recordings, and information storage devices. If you are required to testify, experts advise that you determine who is requesting you to do so and why so that you are sufficiently prepared to provide testimony.

In business cases, legal experts recommend that the company served with a subpoena conduct adequate due diligence to determine the underlying lawsuit or proceeding from which the subpoena was issued. This information may reveal whether the subpoenaed company or one of its officers is the target of a criminal or civil investigation, or whether the company may be joined as a party to the lawsuit. Legal counsel may be necessary to ascertain the optimal way to respond to the subpoena.