A prisoner jailed for 45 years for threatening to kill people and have sex with their corpses has had his sentence reduced to 12 years.
Richard Ford, 39, was serving 30 months for possessing a knife when he wrote threatening letters from his cell at HMP Nottingham in January 2016.
He appealed against his sentence on the basis of an "extraordinarily low IQ".
Court of Appeal judge, Sir Brian Leveson, said the sentence imposed in 2016 was "entirely disproportionate".
Ford, who has spent most of the last 14 years in jail, passed a series of notes to prison officers in which he threatened prison guards, police, a judge and his ex-partner.
The notes included crude drawings depicting his intentions.
At Lincoln Crown Court in December 2016, Judge Michael Heath accepted the 45-year term would be "controversial", but said its length was appropriate as Ford was "highly dangerous".
However, Sir Brian Leveson has slashed the sentence to 12 years' custody with an eight-year licence extension, adding Ford would be able to apply for parole after eight years.
He said the original sentence had "been imposed on a man who never actually assaulted or attempted to assault anyone".
"Plainly, such an overall sentence is entirely disproportionate to the offences which he has committed and cannot be upheld," he said.
"At whatever point he is released, he will remain on licence until 20 years from the date of sentence."
Lawyer's at Ford's appeal hearing earlier this month said he had become "institutionalised", having been in prison for other offences, and committed crimes in order to stay in jail.
"His mixed motive is to ensure that he remains in custody," his barrister, Sam Robinson, told a panel of five judges.
"However, the role of a sentencing judge is to pass a just sentence."