(A) information contained in a financial record of a financial institution, or of a card issuer as defined in section 1602(n)?[1] of title 15, or contained in a file of a consumer reporting agency on a consumer, as such terms are defined in the Fair Credit Reporting Act (15 U.S.C. 1681 et seq.); shall be punished as provided in subsection (c) of this section. (c)The punishment for an offense under subsection (a) or (b) of this section is— (2)(B)a fine under this title or imprisonment for not more than 5 years, or both, in the case of an offense under subsection (a)(2), or an attempt to commit an offense punishable under this subparagraph, if— (i) the offense was committed for purposes of commercial advantage or private financial gain; (ii) the offense was committed in furtherance of any criminal or tortious act in violation of the Constitution or laws of the United States or of any State; or (iii)the value of the information obtained exceeds $5,000; and
一个关系很好的国内外嫁过来的朋友怀疑她老公碰到诈骗，由于最近两人有些矛盾，老公不和她说他在做什么，朋友是无意中发现老公转了很多钱去境外。她不想直接问她老公，想趁老公不在家的时候让我帮着查看她老公的已阅读过的邮件（邮箱一直是登录状态），看里面是否有其他更多证据。她本人英文不好，所以想把电脑拿来我这儿让我看。我不知道我帮她偷看邮件是否会有法律问题？
她不会用电脑，怕自己搞出麻烦。平时关系很好的姐姐，不帮她看也说不过去，就想知道这样帮她我会有麻烦吗？
https://www.law.cornell.edu/uscode/text/18/1030
(a)Whoever—
(2)intentionally accesses a computer without authorization or exceeds authorized access, and thereby obtains—
(A) information contained in a financial record of a financial institution, or of a card issuer as defined in section 1602(n)?[1] of title 15, or contained in a file of a consumer reporting agency on a consumer, as such terms are defined in the Fair Credit Reporting Act (15 U.S.C. 1681 et seq.); shall be punished as provided in subsection (c) of this section. (c)The punishment for an offense under subsection (a) or (b) of this section is— (2) (B)a fine under this title or imprisonment for not more than 5 years, or both, in the case of an offense under subsection (a)(2), or an attempt to commit an offense punishable under this subparagraph, if— (i) the offense was committed for purposes of commercial advantage or private financial gain; (ii) the offense was committed in furtherance of any criminal or tortious act in violation of the Constitution or laws of the United States or of any State; or (iii) the value of the information obtained exceeds $5,000; and朋友是在无意中看到她老公手机里对方发来的收据照片，两人的对话里谈到发邮件等，所以朋友想进一步了解。不过我已经决定不看她老公的邮件了，因为涉及到他人隐私我自己都觉得不合适。再次感谢柠檬的解答。
旁观者应该清楚。既然关系好到考虑一起偷看别人的信件 （即使法律允许，道德上也不应该吧？），跟丈夫说明顾虑才是真正的关心