Famed O.J. prosecutor Christopher Darden's unleashed a nasty string of expletives at his baby mama, according to her ... but Darden's calling BS.
Celia Smith -- who has a nasty history with Darden -- says he's been blasting her regularly ... including earlier this month when he fired off a scorching email, calling her a "dirty nasty low budget porn c*** stripper lot lizard prostitute." The email continued, "You suck and f*** d***s for the whole world to see."
The email came from someone other than Darden, but Smith believes he was using a fake email account. Smith filed docs attempting to get a restraining order against Darden, but the court shot her down -- saying there was no proof he was behind the colorful emails.
Christopher told us he fully denies sending the emails, and added he and his family are the ones getting harassed. He also says there's a Kardashian factor behind Smith's false claims against him.
As we reported ... Darden got a restraining order against Smith last year.