A South Australian woman who posted "vile, vicious and vitriolic" comments about sexual impropriety, incest and drunkenness that were directed at another user of an online political forum has been convicted of stalking.

Key points: Two women aged in their 60s attacked each other in the comments section of The Pickering Post, but a judge found the accused took it too far

Two women aged in their 60s attacked each other in the comments section of The Pickering Post, but a judge found the accused took it too far The accused posted "offensive" comments and even created a new username under the name of the victim's late husband

The accused posted "offensive" comments and even created a new username under the name of the victim's late husband The judge found it "frankly extraordinary" two women of such an age "engaged in such juvenile behaviour"

District Court Judge Julie McIntyre described the behaviour as "juvenile" for two women aged in their 60s.

She said while the victim was not completely blameless in the online slanging match, the accused took it too far and even ignored a police warning for her to stop posting.

The Port Augusta woman — who the ABC has chosen not to name — was found guilty of stalking by a jury in the Port Augusta District Court.

The woman started posting on political forum The Pickering Post — where registered users can comment on articles — in 2013.

"I observe that much of the commentary tendered in evidence does not reflect the best traditions of informed political discourse," Judge McIntyre said during sentencing.

The Pickering Post is a news and opinion blog which was founded by Australian political cartoonist Larry Pickering, who died in November 2018.

Judge McIntyre said the accused started posting in defence of a user called Diddums, who was being targeted by another user, Smart Girl No Really.

Both women engaged in 'mutually derogatory posts'

Commentary between the accused and Smart Girl No Really — who lives in Ballina, New South Wales — started to escalate from there before each woman started to create new usernames in order to insult each other.

"You each engaged in mutually derogatory posts," Judge McIntyre said.

"It is frankly extraordinary that two women of your age engaged in such juvenile behaviour.

"It is even more extraordinary that your behaviour has necessitated police involvement to the extent that it has.

Australian political cartoonist Larry Pickering started the blog The Pickering Post. ( Supplied: The Pickering Post )

"Your conduct is particularly disgraceful because on December 2, 2016, you were cautioned by police following complaints from [Smart Girl No Really].

"This should have been the end of your posts but rather than desisting from this conduct, you escalated it. Many of the posts that were the subject of these charges are vile, vicious and vitriolic."

Judge McIntyre did not repeat the posts in her sentencing, but said they contained unfounded allegations against the victim, her late husband and her parents.

The accused has been a volunteer in Port Augusta

"It is hardly surprising that the jury found them to be offensive, containing, as they did, assertions of sexual impropriety, incest, theft, drunkenness and more," she said.

She said the most appalling posts were under the name of the victim's late husband.

"It is clear that you undertook some research on the internet to find out various matters relating to [the victim] in order to establish this username and to make these posts," she said.

Judge McIntyre imposed a conviction and placed the woman on a good behaviour bond for two years. She also imposed an intervention order, banning the accused from contacting or responding to the victim.

She took into account the fact the accused suffered from post-traumatic stress disorder, had a limited criminal history and was a productive member of the Port Augusta community with her volunteer work.

Editor's note September 30, 2019: This story initially named the sentencing judge as District Court Judge Paul Slattery and said that the judge had "imposed an intervention order, banning any further contact between the two women".

The story has been corrected to refer to District Court Judge Julie McIntyre and state that the intervention order bans the offender from contacting or responding to the victim.