Cloud software like Gmail and e-mail protocols like IMAP make it easy to access your e-mail from any computer. They are also, unfortunately, subject to the Stored Communications Act. The language of the Stored Communications Act is so broad that it seems to apply to any e-mail server (including Exchange servers), whether it is in your office or Google’s data center.
via Is E-mail Secure?.
But the Stored Communications Act, as I read it, does not allow easy access to email server‘s “in your office”–the physical access required generally requires a warrant, whereas it’s usually the 3rd-party nature of storing materials with someone else that makes access by the government easier. Your office IT department is simply not an ISP under the statute, since it does not provide services to the public.
So while, yes, the SCA is a concern, and storing your messages in the cloud is a potential issue if you are in a field like law (where client privacy is critical). But it does not require you to download all your messages to your laptop to get Fourth Amendment protections. Having your company store them is good enough to protect corporate information (i.e., it’s good enough for your company–they could always consent to a search even if you, as an individual, don’t want it).
So, to summarize, if you as an individual want maximum protection from government search, keep everything on your own computer. Corporate materials are safe on a corporation-owned server–but if you have personally private information, that might be subject to the whims of your corporation. Unfortunately, storing your emails on your ISPs server–or in “the cloud,” as with Gmail–offers the least protection, since the government doesn’t need search warrant to get access.
Hopefully, this will change in the future once the law adapts to current technology–but don’t hold your breath.
For more about the Stored Communications Act, see Orin Kerr’s analysis on SSRN: A User’s Guide to the Stored Communications Act, and a Legislator’s Guide to Amending It