Several states already distribute ballots by e-mail or fax, and the NIST report recommends the Election Assistance Commission develop guidelines for doing so. It offers little advice for alternatives to traditional mail for returning ballots, however, saying improvements in security need to be monitored.

"Fax, e-mail and Web-based systems could distribute blank ballots quickly and reliably to voters, significantly reducing the ballot delivery times faced by mailing ballots to voters and improving the ... voting experience for citizens overseas," the report says. "In addition, registration and ballot requests can also take advantage of these distribution methods, but there are more threats when handling personal information from voters. Voted ballot return remains a more difficult issue to address."

NIST's role in election systems is "purely technical," said report co-author Andrew Regenscheid. "NIST does not set or recommend policy decisions," he said. "It is up to state and local election officials to decide what level of risk they are willing to assume, based on the procedures and controls they put in place."