From U.S. EEOC v. Olsten Staffing Servs. Corp., 2009 U.S. Dist. LEXIS 88903 (W.D. Wis. Sept. 28, 2009):

The EEOC authenticates the e-mail through the testimony of Sue Horne, who is the human resources manager for Main Street Ingredients and who personally retrieved the e-mail from Main Street's computer. Olsten argues that only the author of the e-mails may authenticate them, but cites no authority for this proposition and assumes incorrectly that a witness must have personal knowledge of the contents of a document in order to authenticate it. If Olsten were correct, then e-mails would be inadmissible in any case in which the purported author denied their accuracy. The rules of evidence are not so punctilious.

Under Fed. R. Ev. 901, "[t]he requirement of authentication or identification as a condition precedent to admissibility is satisfied by evidence sufficient to support a finding that the matter in question is what its proponent claims." ... Thus, to authenticate the e-mail, the EEOC need only adduce evidence that the document is an e-mail between Olsten and Main Street, not that the contents of the e-mail are the actual thoughts of the author. Testimony from someone who personally retrieved the e-mail from the computer to which the e-mail was allegedly sent is sufficient for this purpose. United States v. Hampton, 464 F.3d 687, 690 (7th Cir. 2006) (custodian of record may authenticate). Further, as the EEOC observes, even without a custodian, e-mails may be authenticated through the e-mail addresses in the headers and other circumstantial evidence, such as the location where the e-mail was found. United States v. Vaghari, 2009 WL 2245097, *8-9 (E.D. Pa. 2009); United States v. Safavian, 435 F. Supp. 2d 36, 39-42 (D.D.C. 2006).

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Olsten next attacks the exhibit as inadmissible hearsay. Olsten focuses on the e-mail from Main Street [the non-party recipient of the principal email], arguing that it does not fall into the hearsay exception for admissions by a party-opponent under Fed. R. Ev. 801(d)(2). This is true, but irrelevant. The e-mail from Main Street is not hearsay because the EEOC is not offering it for the truth of the matter asserted by Main Street, see Fed. R. Ev. 801(c), but for the effect the e-mail had on Olsten [the party-sender of the principal email]. United States v. Inglese, 282 F.3d 528, 538 (7th Cir. 2002) (out-of-court statement not hearsay when offered to show effect it had on listener). [Defendant] Olsten does not challenge [its employee] Boehme's e-mail on hearsay grounds, presumably due to Rule 801(d)(2)(D).

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[No Rule 37(c)(1) Prejudice from 26(a)(1) Nondisclosure of Person Actually Deposed]

Finally, Olsten argues in a footnote that the e-mail should be stricken because the EEOC did not disclose Horne as a potential witness before summary judgment. This undeveloped argument is unpersuasive, particularly because Olsten had deposed Horne by the time it objected to the admissibility of the e-mails. It is difficult to imagine any unfair prejudice that Olsten would have suffered as a result of any untimely disclosure. See Fed. R. Civ. P. 37(c)(1)(A) (exclusion of witness testimony for failure to disclose not required when failure was harmless). The bottom line is that the Boehme's e-mail is admissible evidence that the court will consider in deciding Olsten's motion for summary judgment.