we also "have no idea" what e-mail accounts, or what types of e-mail accounts, the government might investigate. Toilet Goods Ass'n, Inc. v. Gardner, 387 U.S. 158, 163 (1967). That uncertainty looms large in a debate about the expectations of privacy in e-mail accounts. The underlying merits issue in the case is this: In permitting the government to search e-mails based on "reasonable grounds," is 2703(d) consistent with the Fourth Amendment, which generally requires "probable cause" and a warrant in the context of searches of individuals, homes and, perhaps most analogously, posted mail? The answer to that question will turn in part on the expectations of privacy that computer users have in their e-mails — an inquiry that may well shift over time, that assuredly shifts from internet-service agreement to internet-service agreement and that requires considerable knowledge about everevolving technologies. Because "[t]he task of generating balanced and nuanced rules" in this area "requires a comprehensive understanding of technological facts," Orin S. Kerr, The Fourth Amendment and New Technologies: Constitutional Myths and the Case for Caution, 102 Mich. L. Rev. 801, 875 (2004), Warshak's claim epitomizes the kind of dispute that would profit from "a concrete factual context," Ammex, 351 F.3d at 706.