Two cases:

Case No. 1. Eastview Healthcare, LLC v. Synertx, Inc., 2009 Ga. App. LEXIS 225 (Ga. App. Mar. 3, 2009) (a litigation involving multiple related cases):

The facilities [i.e., the defendants in this case] claim that the court erred in sustaining [plaintiff] Synertx's objections to evidence attached to their responses to the company's motions for summary judgment and in striking the evidence and the statements of fact which relied upon such evidence. ***

[T]the facilities contend that several e-mails ... were admissible without the necessity of proving their authenticity because the e-mails had been produced by the plaintiff in the main action, Synertx. The facilities' reliance on Willis v. Hill, 116 Ga. App. 848, 871 (6) (159 S.E.2d 145) (1967), rev'd on other grounds, Hill v. Willis, 224 Ga. 263 (161 S.E.2d 281) (1968), in support of their argument is misplaced. In Willis, the plaintiffs produced documents pursuant to the defendant's notice to produce, and the defendant sought to use the documents as evidence against the plaintiffs.... The Court held that, "[u]pon production of copies pursuant to a notice to produce, the producing party admits the correctness of the copies and further proof is unnecessary in order for the moving party [, i.e., the requesting party,] to introduce them into evidence." ...

In these cases, however, the records clearly show that Synertx did not produce the e-mails, but that the facilities (the defendants in the main action) produced a few of the e-mails during discovery. Thus, because the facilities produced the e-mails and were relying on them to support their counterclaims and defenses, the facilities are deemed to have admitted to the correctness and authenticity of the documents, and Synertx was authorized to introduce the e-mails as evidence against the facilities without providing further proof of authenticity.... In contrast, however, because Synertx neither produced the e-mails nor claimed any benefit pursuant to them, the facilities were not authorized to use the e-mails in support of their claims or defenses against Synertx without producing further proof of the e-mails' authenticity. See Campbell v. Roberts, 66 Ga. 733, 734-735 (1881) (the administrator of an estate produced a deed during discovery which purported to convey property to the opposing party, but which lacked any proof of delivery to the claimant; under such circumstances, the claimant could not use the deed as evidence against the administrator without further proof of authenticity, since it was the claimant, not the administrator, who sought to benefit under the deed).

Held, “the trial court did not abuse its discretion when it sustained Synertx's objections to the admissibility of the e-mails and granted the motion to strike.”

Case No. 2. Schaghticoke Tribal Nation v. Kempthorne, 587 F. Supp. 2d 389 (D. Conn. 2008):

Respondents also move to strike numerous emails sent to and from the lobbying firm Barbour Griffith & Rogers ("BGR") for lack of authentication and as inadmissible hearsay. However, these emails have been properly authenticated to the extent that they were produced to Petitioner by BGR itself during discovery. See John Paul Mitchell Sys. v. Quality King Distribs., Inc., 106 F. Supp. 2d 462, 472 (S.D.N.Y. 2000) (holding that the act of production itself implicitly authenticates documents). They also were identified at Loren Monroe's deposition. See Fed. R. Evid. § 901(b) (providing that "[t]estimony that a matter is what it claimed to be" is an example of identification which satisfies the authentication requirement of Rule 901(a)).