In May, Rebecca Ellen Stephine Sheehan, 38, was stopped by police after a person matching her description was seen looking inside letterboxes in Leith St, the Dunedin District Court heard this week.
When asked by police what was in her bags, she presented a blue cooler bag with a sports drink and another tote bag inside.
Hidden inside the tote were several letters addressed to other people.
A month later, Sheehan was walking along Maitland St when she noticed an envelope sticking out of a letterbox.
The police summary said she spontaneously took the letter and opened it, finding a Z fuel card inside.
Then, in the space of two days, the mailbox thief used the fuel card repeatedly at Z Andersons Bay, racking up a bill of $156.26.
Counsel Sophia Thorburn said her client’s offending was "opportunistic in nature" and Sheehan had been experiencing significant financial hardship.
Ms Thorburn also said Sheehan was affected by her partner’s ongoing health problems.
During sentencing, Judge David Robinson acknowledged Sheehan had a lot going on in her personal life.
On two charges of unlawfully opening a postal article and one of dishonestly using a document for financial gain, Judge Robinson sentenced her to nine months’ supervision and ordered her to repay the fuel card spend.