"In United States v. Barnes, 803 F.3d 209 (5th Cir. 2015), the Fifth Circuit held that the government laid a sufficient foundation to support the admission of the defendant's Facebook messages under Rule 901 where a witness testified that she had seen the defendant using Facebook and that she recognized his Facebook account as well as
his style of communicating as reflected in the disputed messages. In United States v. Hassan, 742 F.3d 104 (4th Cir. 2014), the Fourth Circuit held that the government properly linked the Facebook pages at issue to the defendants by using internet protocol addresses to trace the Facebook pages and accounts to the defendants' mailing and email addresses. And in Vayner, the Second Circuit held that the government failed to adequately authenticate what it alleged was a printout of the defendant's profile page from a Russian social networking site where it offered no evidence to show that the defendant had created the page. 769 F.3d at 131.
In all of these cases, the courts considered a variety of extrinsic evidence to determine whether the government had met its authentication burden under Rule 901—each reiterating, in the course of that analysis, that conclusive proof of authenticity is not required and that the jury, not the court, is the ultimate arbiter of whether an item of evidence is what its proponent claims it to be."
United States v. Browne, 834 F.3d 403, 413 (3d Cir. 2016)