But Setka appeared unfazed as he left Melbourne Magistrates Court on Wednesday, telling reporters he was "happy" about the threats.
The former head of the Victorian branch of the CFMEU is accused of sending his own threatening, offensive and abusive emails to the union's then-administrator Mark Irving.
Police allege Setka, 61, sent the emails last year after receiving a production notice and then a follow-up letter.
He has been charged with 11 counts of using a communication device to menace, harass and offend.
According to charge sheets released by the court, Setka allegedly emailed nine abusive messages between October 27 and October 30.
"If you want the paperwork maybe go and have a colonoscopy, you might find them there," one of the messages allegedly read.
"Or maybe get Albo a colonoscopy, but you would only find yourselves up there because that's how far up his arse you dogs are."
Setka is also accused of using a carriage service in a menacing manner on Christmas Day.
"Hope you both have a shit Xmas, you no good sell out c****," the message allegedly read.
"Go and have a sook to the hawk task force you weak woke f******."
Setka's lawyer on Wednesday sought an adjournment of the case, telling the court he had requested material from Victoria Police and the CFMEU but was still awaiting disclosure.
Prosecutor Alex Turner said police would be objecting to the release of at least four documents, citing issues around relevance.
Another two documents sought from the police were not actually in their possession and instead needed to be requested from the CFMEU, Mr Turner said.
Magistrate William Parker adjourned the case off to a special mention hearing in September where a contest over the documents will be heard.
When the magistrate then raised applications from the media to access documents, Setka's lawyer told the court his client had been subjected to threats to kill.
The police were still investigating the threats, the lawyer said as he sought for Setka's address to be redacted from the released charge sheets.
Outside court, Setka was asked by reporters how he felt about the threats.
"Happy," he answered before continuing to walk away.
Setka was head of the Construction, Forestry, Maritime and Energy Union in Victoria for 12 years but he stepped down in 2024 following a Nine investigation into criminal links within the construction industry.
The reporting alleged major Victorian and NSW construction projects had been infiltrated by underworld figures and bikies acting as union delegates.
Setka said the allegations against the union were false but said he would step down to stop the barrage of stories.
He is separately facing legal action by the Fair Work Ombudsman over allegations he tried to coerce the AFL into sacking its chief umpire.