An estate agent told a court she was sent a "threatening" email by a Hells Angel accused of attacking a biker.
Nicola Bowler said Oliver Wilkinson attached an article headlined "Biker partially blinded in attack by Hells Angels" to the email.
At the Old Bailey, Mr Wilkinson, of St Leonards, and Matthew Barnes deny attacking Christopher Harrison outside a Hastings pub in February 2016.
They have pleaded not guilty to causing grievous bodily harm with intent.
The court heard previously that Mr Harrison had suffered serious eye injuries.
Mr Harrison has alleged former Sussex chapter president Mr Barnes, 48, of Hastings, head-butted him and Mr Wilkinson, 50, punched him.
Ms Bowler told the jury she had emailed Mr Wilkinson and his wife Jane in March to tell him their application to rent a property was rejected due to credit checks showing debts in excess of £20,000.
She told the court she received an email response from the address Mr Wilkinson had provided saying: "Well, you leave me no other option but to take matters into my own hands.
"I suggest you read the attachment and see what happens when idiots rip me off. Sleep well."
Ms Bowler told the jury: "I was worried, I was worried for my family. It made me feel he was going to visit me at my home.'
Det Con Stuart Black was then called to the stand to confirm a number of Mr Wilkinson's previous convictions.
They include possessing a knife and knuckledusters and behaving in a threatening way in 2004.
Mr Wilkinson was convicted of making threats to kill in 2005 after warning a council worker he would "take the law into my own hands, as I have done before", the court was told.
In 2009 he used threatening words and behaviour to a staff member at a takeaway who put salad on his kebab without his permission, the jury heard.
Mr Barnes, of Victoria Avenue, and Mr Wilkinson, of Duke Road, St Leonards, deny causing grievous bodily harm with intent.
The trial continues.