• President Trump's use of "at least two Twitter accounts" (the official @POTUS and his longtime handle, @realDonaldTrump) and his penchant for deleting some tweets. The lawmakers said that if those deleted tweets "were not archived it could pose a violation of the Presidential Records Act."
• The reported use by federal employees of encrypted chat apps "that could result in the creation of presidential or federal records that would be unlikely or impossible to preserve." Confide, Signal and WhatsApp in particular get mentions in the letters. "The need for data security ... does not justify circumventing requirements established by federal recordkeeping and transparency laws," the lawmakers said.

Why this matters: The White House and the federal government are required to preserve records under the law, and new technology raises questions about how those laws should keep up with the times. The Oversight Committee has also been under pressure from liberals to investigate Trump with the same fervor with which it pursued the Obama administration

What's next: The lawmakers, Oversight Chairman Jason Chaffetz and ranking member Rep. Elijah Cummings, ask several questions in their letter to McGahn. Their inquiries focus both on what the White House's policies are for electronic messages and which senior officials who fall under the records law "have used an alias email account to conduct official business since January 20, 2017." They want a response from the White House and the agencies by March 22.