The Leader of the House of Commons suggested on Monday she has perceived a minute earnest to “take lives”.
The Conservative MP appears to have been targeted due to her support for Brexit.
The letter, sealed by “THE REAL 48 PER CENT”, reads: “If you try to take divided partial of someone’s identity, there are consequences.
“We have watched as you have led us to the corner of the abyss. We will watch no longer.
“You have taken lives on the side. Now we will take lives on yours.
“We are coming for you.”
Posting an picture of the minute on Twitter, which was addressed to her in Parliament, Ms Leadsom commented: “Pretty inhuman whoever sent me this.
“We live in a democracy – death threats since you don’t agree? And unsigned? Coward…”
Last week, associate Leave-supporting Tory MP Zac Goldsmith pronounced a identical minute had been sent to an 80-year-old in his Richmond Park constituency.
The Guido Fawkes website reported 6 distinguished Leave donors had also perceived identical letters.
Late last year, Remain-supporting Conservative backbencher Dominic Grieve was forced to report death threats to police after heading efforts to better the Government on flagship Brexit legislation.
Other Tory Remainer rebels, who have been dubbed “mutineers”, have also formerly suggested death threats.
Ms Leadsom was a distinguished member of the Vote Leave campaign during the EU referendum and argued for Brexit in a inhabitant TV debate.
She also challenged Theresa May for the Conservative care in 2016 before withdrawing from the race.
Last week, the Prime Minister used a discuss imprinting the centenary of some women being given the opinion to advise of a “coarsening” of open debate.
“The ideal of a truly plural and open open globe where everybody can take partial is in danger,” Theresa May said.
“A tinge of sourness and charge has entered into the open debate.
“In open life, and increasingly in private conversations too, it is apropos harder and harder to control any domestic discussion, on any issue, but it forward into tribalism and rancour.
“Participants in internal and inhabitant open life – from possibilities and inaugurated member to campaigners, reporters and commentators – have to contend with unchanging and sustained abuse.
“Often this takes the form of sincere intimidation.”