Gartner analyst John Pescatore, whose background includes working with the Secret Service, says NSA-approved devices like Sectera would be secure enough for use in a closed system, but the problem is switching to unclassified mode to use the Internet.
"Internet e-mail is totally unacceptable for a president to use," Pescatore says. "There is no strong authentication — how can anyone prove an e-mail came from the president? There is no integrity — how can anyone prove the content wasn't changed?"
Use of something like the PGP public-key infrastructure could help the president communicate with others in a larger closed system, says Pescatore, "But that doesn't stop anyone from forwarding an e-mail from him outside that closed loop."
Pescatore says he would also be concerned that any wireless device might act as a radio-frequency beacon to reveal the president's location.
The other challenge — the legal requirement under the Presidential Records Act that a president store all documents in order to make them available to the public in the future — is also a factor Obama and his team must consider.
Most legal experts and scholars say there's nothing in the Presidential Records Act to prevent use of e-mail.
"What it does do," says Dickinson College political-science professor Andrew Rudalevige, "is make every presidential e-mail a public record and thus something — unless classified for other reasons, such as national security — will be released via the presidential library system."
Records are typically deemed "open" 12 years after the president leaves office, but can be opened by presidential consent, by the Freedom of Information Act or subpoena before then, he adds.
However, current law doesn't require presidential phone calls to be recorded, though they have to be logged.
So, between the Presidential Records Act and the threat of PDA hacking, presidents have some good reasons to avoid e-mail, Rudalevige notes.