Boston was reportedly the origin of a bogus white powder attack that sent President Trump’s daughter-in-law to the hospital as a precaution — the second such mail scare aimed at the first family that was traced back to the Hub.

Vanessa Trump opened the letter containing an unidentified white powder that was addressed to her husband, Donald Trump Jr., yesterday morning at her mother’s midtown Manhattan apartment.

She then dialed 911, saying she was coughing and feeling nauseous.

Three people were taken to the hospital as a precaution, according to the New York Fire Department.

The letter was postmarked from Boston, according to several published reports, citing anonymous law enforcement sources.

Even though the white powder was found to be harmless, the frightening incident has raised questions about the protection of the president’s kin.

In March 2016, during the GOP primary, a threatening letter with white powder — also reportedly originating from Boston — was sent to Trump’s other son, Eric, that promised: “If your father does not drop out of the race, the next envelope won’t be a fake.”

Donald Trump Jr. praised first-responders and investigators yesterday thanking them via Twitter “for their decisive action and incredible words of support to my wife and family.”

He called the hoax “truly disgusting” and “disturbing behavior.”

A former Secret Service agent told the Herald it’s also a wake-up call for those charged with protecting the Trump family.

“This is a leading indicator of a much larger problem — it’s not an isolated incident,” said Jonathan Wackrow, managing director of Teneo Risk, and a former Secret Service agent who has protected former President Barack Obama and his family.

Vanessa Trump doesn’t technically qualify for Secret Service protection, said Wackrow. But he added that the suspect may be doing “continuous testing” to see how close he or she can get to the president.

Even though it’s unrealistic anyone will ever successfully sneak a contaminated letter through all the White House safeguards directly to the president, the suspect now knows that white powder in an envelope — reminiscent of the anthrax scares in the weeks after the Sept. 11 attacks — can still reach Trump’s close family and set off panic.

“The incident alone highlights a major vulnerability that someone has exploited that they can get that close to a member of the Trump family,” said Wackrow. “So protocols need to be adjusted.”

He said mail screening is typically a “risk-tiered approach,” with the highest priorities focusing on detecting explosives.

Screening for chemical agents takes longer, usually must be done in an isolated facility, and often only if there’s specific intelligence.

The Secret Service, in a statement, confirmed it’s conducting an “active investigation,” but declined to reveal details.

Laurel J. Sweet and Herald wire services contributed to this report.