At least six current and former advisers to President Trump have reportedly used private email addresses occasionally for White House business, a revelation Trump critics are likely to pounce upon in light of the scandal that brought down Hillary Clinton in 2016 — despite significant differences.

Politico reported Sunday that Jared Kushner, Trump’s son-in-law and senior adviser, had occasionally used a private email address to send or receive work-related emails. The New York Times reported late Monday that Kushner was not the only adviser to use a private address.

Former White House Chief Strategist (now executive chairman of Breitbart News) Steve Bannon, former Chief of Staff Reince Priebus. National Economic Adviser Gary Cohn, and adviser Stephen Miller, all have sent “at least a few emails on personal accounts,” according to the Times. Ivanka Trump — Trump’s daughter and Kushner’s wife — also used a private account when she served as an unpaid adviser, according to the Times.

Kushner’s case, in particular, is likely to raise eyebrows as he established his own domain, IJKFamily.com in December to host his family’s personal email, according to the Times. The outlet reports that the domain was hosted by GoDaddy on a server in Arizona.

Government officials are to use official email for government business for both security and oversight purposes. This rule was cast into the national headlines in the 2016 presidential campaign after it was revealed that Hillary Clinton had used a private homebrew server to conduct her business when she served as secretary of state.

While questions into “private email use” are likely to draw cries of hypocrisy from Trump opponents, noting that Trump savaged Clinton for her use, the revelations about Trump officials show yawning differences from Clinton’s.

In Kushner’s case, it appears he used private email occasionally, not exclusively; the number of emails are consequently significantly smaller than Clinton’s (dozens compared with tens of thousands). There is no indication he sent or received classified emails, and none of the emails appear to have been deleted. Most instances are claimed to be instances of someone sending him an email like a news hit or a piece of commentary. Also, there is no sign that he used a private server to conduct business.

The Times notes that it is not illegal to use a personal address as long as the emails are forwarded to the government address, something which Kushner claims to have done. However, the issue is likely to prove tricky for the White House, and White House Press Secretary Sarah Huckabee Sanders indicated that the administration has a strict policy on such matters.

“All White House personnel have been instructed to use official email to conduct all government-related work,” Sanders said. “They are further instructed that if they receive work-related communication on personal accounts, they should be forwarded to official email accounts.”

The email usage could eventually find the White House facing the prospect of more committee hearings, amid the already long line of hearings related to the probe into alleged Russian interference in the 2016 election.

House Oversight Committee Chairman Trey Gowdy (R-SC) and ranking Democrat Elijah Cummings (D-MD)  wrote to White House counsel Don McGahn and leaders of two dozen federal agencies Monday requesting information about the use of personal email accounts by members of the Trump administration. The committee was central in the probe into Clinton’s emails.

The Gowdy/Cummings letter asks for the names of any non-career official who has used a personal account for official business and the names of any officials who use “text messages, phone-based message applications, or encryption software.” The letter reportedly says that the requests are in order to see whether the administration is following record retention laws.

Clinton herself seized on the revelations Monday, declaring: “It just goes to the rank hypocrisy that this Trump campaign and now this Trump White House is engaged in.”

Adam Shaw is a Breitbart News politics reporter based in New York. Follow Adam on Twitter: @AdamShawNY.