18 U.S.C. § 2701 : US Code - Section 2701: Unlawful access to stored communications

      (a) Offense. - Except as provided in subsection (c) of this
    section whoever - 
        (1) intentionally accesses without authorization a facility
      through which an electronic communication service is provided; or
        (2) intentionally exceeds an authorization to access that
      facility;

    and thereby obtains, alters, or prevents authorized access to a
    wire or electronic communication while it is in electronic storage
    in such system shall be punished as provided in subsection (b) of
    this section.
      (b) Punishment. - The punishment for an offense under subsection
    (a) of this section is - 
        (1) if the offense is committed for purposes of commercial
      advantage, malicious destruction or damage, or private commercial
      gain, or in furtherance of any criminal or tortious act in
      violation of the Constitution or laws of the United States or any
      State - 
          (A) a fine under this title or imprisonment for not more than
        5 years, or both, in the case of a first offense under this
        subparagraph; and
          (B) a fine under this title or imprisonment for not more than
        10 years, or both, for any subsequent offense under this
        subparagraph; and

        (2) in any other case - 
          (A) a fine under this title or imprisonment for not more than
        1 year or both, in the case of a first offense under this
        paragraph; and
          (B) a fine under this title or imprisonment for not more than
        5 years, or both, in the case of an offense under this
        subparagraph that occurs after a conviction of another offense
        under this section.

      (c) Exceptions. - Subsection (a) of this section does not apply
    with respect to conduct authorized - 
        (1) by the person or entity providing a wire or electronic
      communications service;
        (2) by a user of that service with respect to a communication
      of or intended for that user; or
        (3) in section 2703, 2704 or 2518 of this title.