Larry Ellison has renewed his one-man offensive on the HP board, launching a savage attack about the appointment of Léo Apotheker as the company's new chief executive.
In an email sent to the Wall Street Journal, Ellison claimed he was "speechless" at the news of the former SAP chief executive's appointment, before finding plenty to say.
"HP had several good internal candidates…but instead they pick a guy who was recently fired because he did such a bad job of running SAP," Ellison wrote.
"None of the HP board members own much HP stock so they have little to lose. But the HP employees, customers, partners and shareholders will suffer. The HP board needs to resign en masse, right away. The madness must stop."
In another email, sent to the Financial Times, Ellison also attacked Apotheker over his tenure at SAP when the company is alleged to have been stealing Oracle's intellectual property.
"SAP has already publicly confessed and accepted financial responsibility for systematically stealing Oracle’s intellectual property. Much of this industrial espionage and intellectual property theft occurred while Apotheker was CEO," he wrote.
SAP has conceded both copyright and computer violations but claims the damage to Oracle only runs to tens of millions of dollars, not the $1bn Oracle is after.
Ellison had previously criticised HP over the way it treated former chief executive Mark Hurd, and then faced down a legal challenge from the firm when he hired Hurd to join the board of directors at Oracle.
Recently, when the firms announced an end to the legal action, they pledged to continue their work together, but clearly the dust has still not settled as far as Ellison is concerned.
HP said it had no comment to make on the matter.
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