Last year, Margaret Denise Kronfeld (52), of Auckland, went on trial in the Dunedin District Court, where Judge Michael Crosbie found her guilty of criminal harassment and three charges of accessing a computer system without authority.
She pleaded guilty to two Telecommunications Act counts during the trial and was later sentenced to 120 hours’ community work.
In the High Court last year, Kronfeld challenged the convictions.
Defence counsel Andrew Speed said the harassment charge was essentially based on five emails sent by his client on April 5, 2015.
However, all but one of those emails was used to support other charges which had either been dismissed or admitted.
Mr Speed said that raised issues of "double jeopardy".
Justice Nicholas Davison agreed.
"The appeal against conviction on the charge of criminal harassment has succeeded on what is a technicality," he said.
Because of the way the charges were laid, only one email remained valid and that was not enough to prove the charge.
"There were many other emails which could have founded the charge of criminal harassment," Justice Davison noted.
The lewd and offensive content of some of those communications was revealed in the recently released judgement.
Using various aliases, Kronfeld questioned the fidelity of the man with whom she had had an illicit affair.
Over months, the defendant abused the woman, calling her "spineless" and telling her she was "married to a man with a hungry, wandering penis".
The court heard at trial how Kronfeld met the married man — whose name was suppressed — at an Auckland conference in 2011.
After a host of romantic liaisons around the country, things soured between the pair.
Three years after the affair began, Kronfeld issued an ultimatum, telling the man to choose between her and his wife.
When he opted to remain with his wife, the "disgraceful" conduct started.
While Kronfeld’s appeal against the harassment conviction was successful, the appeal for accessing a computer system failed.
She had argued her lover had willingly given her a password to an electronic account that she had later used when they had split.
Kronfeld accessed their daughter’s high school hub as well as an email account the couple used, which shared the same password, the court heard.
"Just because Ms Kronfeld had been told the password to access [an] account, that did not constitute express or implied authority in order to access any other account, or access that account when any authority was spent," Justice Davison said.
An appeal against sentence will be heard by the High Court later this year.
