Reports emerged last month that both senior aides had previously used their respective personal accounts for official information, but on Monday, Politico reported of a third and previously unreported address.
Shared by the Kushner family, that third account received hundreds of emails from White House addresses, including non-public travel documents, internal schedules and official White House materials, Politico said, citing unnamed sources.
It's now being examined by White House officials, the outlet added, as the Trump administration launches a probe into private e-mail use by senior aides, including Kushner and his wife.
A Kushner family representative told Politico that Ivanka Trump has been careful about keeping her personal life apart from official business, the outlet said. The representative added that her emails have been preserved: "The extent of this coordination illustrates both full transparency and a desired separation between her work and personal functions," Politico reported the person as saying.
According to the report, Kushner's lawyer said his client "uses his White House email address to conduct White House business" and that use of the private account was in most cases initiated by someone else.
A White House spokesman told CNBC that staff are instructed to "fully comply with the Presidential Records Act and applicable guidelines for work-related communications," adding that "in light of recent congressional inquiries, we have briefed staff on the need to preserve records and working to ensure compliance."