A federal court has ordered Hillary Clinton to answer written questions from a conservative legal advocacy group about her emails.
The ruling spared the Democratic presidential nominee the embarrassment of having to give sworn testimony in the lawsuit.
Judge Emmet G Sullivan issued the order on Friday as part of a long-running public records battle by Judicial Watch.
He gave the group until 14 October to submit the questions and Mrs Clinton has 30 days to respond.
Her campaign has been dogged by her use of an unauthorised private email system containing classified information during her tenure as Secretary of State.
The FBI closed its investigation last month without recommending criminal charges, though it called her arrangement "extremely careless".
The issue has fuelled public distrust of Mrs Clinton, which Republicans are seeking to capitalise on ahead of November's election.
This week the FBI delivered to Congress the notes from its investigation into Mrs Clinton's emails, as politicians plan further hearings.
Earlier this month, Judicial Watch released a fresh batch of newly uncovered Hillary Clinton emails, obtained under the Freedom of Information Act.
The messages raised questions about the nature of her State Department's relationship with the Clinton Foundation.
In a 2009 email, a top foundation official lobbied Clinton aides to employ an associate at the State Department.
In another message that year, the same official made inquiries on behalf of a billionaire donor to the foundation.
He badgered Mrs Clinton's aides to put the Lebanese-Nigerian tycoon in touch with the State Department's "substance person" on Lebanon.
Republican presidential nominee Donald Trump's campaign said the new emails were evidence of Mrs Clinton being corrupt.