“There but for the grace of God go all of us,” said Tommy Vietor, a former National Security Council spokesman for President Obama who now works in San Francisco. He said thinking about his own email exchanges in Washington made him cringe, even now.

“Sometimes we’re snarky, sometimes we are rude,” Mr. Vietor said, recalling a few such moments during his time at the White House. “The volume of hacking is a moment we all have to do a little soul searching.”…

On Capitol Hill, Senator Richard J. Durbin of Illinois, the chamber’s No. 2 Democrat, said the news of Mr. Powell’s hacked emails had him thinking that Senator Chuck Schumer’s never-ending use of an old-fashioned flip phone “makes more sense than ever.”

“I think more and more people are realizing that there isn’t a thing you can say in an email that isn’t likely to be hackable or discoverable at some later point,” Mr. Durbin said, lamenting his own complacency.