A Sydney radiologist who admitted she was "hell-bent on revenge" has been jailed for nine months after sending thousands of abusive and threatening messages to a former Tinder date.

Key points: Denise Lee insisted she was not a "bunny boiler" in one of her messages

Denise Lee insisted she was not a "bunny boiler" in one of her messages A 'bunny boiler' is a woman who acts vengefully after breaking up with a partner

A 'bunny boiler' is a woman who acts vengefully after breaking up with a partner She targeted Matthew Holberton's new partner after he moved to Melbourne

Denise Jane Lee, 41, went on 10 dates in four months with Matthew Holberton after meeting on the app in July 2015, but within months she vowed to target "whatever you value most".

When Mr Holberton tried to break it off, Lee bombarded him with an initial 69 texts in under two hours, which ranged from "I want us to try properly" to "I am going to f*** your life up".

Lee insisted she was "not a bunny boiler" in one of her later messages.

Magistrate Michael Barko told Downing Centre Local Court the matter involved "the most detailed and extraordinary proceedings" he had dealt with.

"In my 34 years of criminal justice in NSW I've never seen a case like this before," he said.

When Mr Holberton blocked Lee's number, she continued the abuse by creating multiple other identities, including "MouldyCheese99" and "PatrickBateman2000".

Lee walked into the hearing 20 minutes late wearing a face mask and immediately began coughing, before sitting quietly and taking notes.

The court heard she admitted in messages to being "hell-bent on revenge".

"You're a f***ing piece of work and you will get everything you deserve," she wrote to Mr Holberton.

Matthew Holberton went on 10 dates with Denise Lee. ( AAP: Joel Carrett )

When Mr Holberton moved to Melbourne and began another relationship, Lee targeted his new partner and included the woman's colleagues and mother in further emails.

Mr Barko said the content was at least defamatory and slanderous, if not "vile, despicable and offensive".

Referring to the new partner's social media posts, Lee slung insults including "hagged mutton face", "ugly, attention-seeking slag" and "you have a beak like an eagle".

Lee was initially charged with 10 offences including multiple counts of using a carriage service to menace, but last year she pleaded guilty to four charges and the remaining were dropped following negotiations with prosecutors.

Mr Barko sentenced her to nine months in jail and a two-year community corrections order, including 200 hours of community service.

He said the community must understand "gutless and cowardly" use of communication tools came with serious ramifications.

The court heard Lee used 38 different email addresses, including Protonmail and VPN services to conceal the sender's details.

Mr Barko said Lee was clearly an "extremely bright, intelligent woman", having previously achieved a perfect 100 per cent tertiary entrance rank.

He acknowledged mental health issues and prolonged proceedings but said the latter was partially a result of her spending "hundreds of thousands of dollars" on legal fees.

Mr Barko began the sentencing by quoting English dramatist William Congreve, who famously wrote: "Heaven has no rage, like love to hatred turned, Nor Hell a fury, like a woman scorned".

Lee appealed the decision and was subsequently granted bail to reappear in court next month.