Tanya Maree Quattrocchi, 23, pleaded guilty earlier this month to four charges of cyber-stalking for hacking into DeGarmo's My Space account and intercepting her e-mails and those of her mother, Brenda, and housemate, model Donielle Morris. DeGarmo was the 2004 runner-up in the U.S. television singing contest.
The Victoria state County Court sentenced Quattrocchi, of Melbourne, to 26 months in prison. She will be eligible for parole after 12 months.
Judge Lisa Hannan described Quattrocchi's offenses as serious, especially considering they began only six months after she was convicted on similar charges.
In 2007, Quattrocchi was sentenced to 150 hours of community service for cyber-stalking and blackmailing DeGarmo in 2006.
She has been in custody since January when she was arrested as she sat a computer typing an e-mail pretending to be DeGarmo's mother. The new convictions are for offenses since November 2007.
Hannan said the stalking affected every aspect of DeGarmo's life, adding that she felt constantly vulnerable.
Since "American Idol," DeGarmo has released an album "Blue Skies" and appeared on Broadway in "Hairspray."