From Alamar Ranch, LLC v. County of Boise, 2009 U.S. Dist. LEXIS 101866 (D. Idaho Nov. 2, 2009):

Does use of work e-mail waive any privilege? Although there are no Ninth Circuit cases on-point, cases from other jurisdictions have developed a four factor test to balance the expectation of privacy against the lack of confidentiality: (1) Is there a company policy banning personal use of e-mails?; (2) Does the company monitor the use of its e-mail?; (3) Does the company have access to all e-mails?; and (4) Did the company notify the employee about these policies? See In re Asia Global Crossing, Ltd., 332 B.R. 247, 257 (S.D.N.Y. 2005).

Applying similar factors, one court found that an employee waived the attorney-client privilege by communicating with her attorney over her work e-mail system where the company policy clearly notified all employees that e-mails were "subject to monitoring, search or interception at any time . . . ." Kaufman v SunGard Inv. System, 2006 WL 1307882 (D.N.J. May 10, 2006). In a similar case, although not involving the attorney-client privilege, a court found that the employee had no reasonable expectation of privacy in files he stored in his personal folder on his computer and in his personal e-mail account because his employer had an "explicit policy banning personal use of office computers and permitting monitoring" and because the employer retrieved such information by accessing its own computer network. See Thygeson v. Bancorp, 2004 WL 2066746 at *21 (D.Or. Sept. 15, 2004). The court found that the employer "retained the key" to plaintiff's files as it "was able to remotely search [plaintiff's] personal files on the network." ***

However, an employer with a similar monitoring policy went too far when it accessed e-mails that an employee had sent via her work computer using a personal web-based e-mail account, and the employee worked at home where the employer could not carry out the regular monitoring policy it applied to on-site use. See Curto v. Medical World, 2006 WL 1318387 (E.D.N.Y., May 15, 2006). Even when an employer had the ability to monitor an employee's e-mail, one court refused to find a waiver where the employee was communicating with her attorney from a work computer through a personal password-protected web-based e-mail site. See Stengart v. Loving Care Agency, Inc., 973 A.2d 390 (N.J. Super. A.D. 2009).

In the present case, Kirkpatrick [the employee] did not attempt to protect the confidentiality of the messages by using a web-based password-protected e-mail account. She simply used her work e-mail. Thus, \Stengart does not apply here, and the Court leaves for another day whether there is waiver when the employee attempts to protect work-based e-mails through a personal password-protected web site.

This case presents a simple scenario where the IHFA put all employees — including Kirkpatrick — on notice that their e-mails would (1) become IHFA's property, (2) be monitored, stored, accessed and disclosed by IHFA, and (3) should not be assumed to be confidential. While Kirkpatrick states that she was not aware of any company monitoring ... the Court's earlier discussion of the legal standards makes clear that her "bare assertion that [she] did not subjectively intend to waive the privilege is insufficient to make out the necessary element of nonwaiver." Weil, 647 F.2d at 25. It is unreasonable for any employee in this technological age — and particularly an employee receiving the notice Kirkpatrick received — to believe that her e-mails, sent directly from her company's e-mail address over its computers, would not be stored by the company and made available for retrieval.

Accordingly, the Court finds that Kirkpatrick waived the privilege for those messages she sent from her work computer. With regard to the e-mails Charney [the employee’s attorney] sent to her, there is no question that her address — "JeriK@IHFA.org" — clearly put Charney on notice that he was using her work e-mail address. Employer monitoring of work-based e-mails is so ubiquitous that Charney should have been aware that the IHFA would be monitoring, accessing, and retrieving e-mails sent to that address. Given that, the Court finds that Charney's e-mails sent to Kirkpatrick's work e-mail are likewise unprotected by any privilege.