She also directed all of the mail for this account to her home address.
Nearly 500 cheques were deposited into the account she controlled, from which she withdrew cash - up to $850,000 in one year.
Prosecutor Erin Woolley told the court that "errant journal entries" were made in conjunction with Mosese diverting these cheques from Mainfreight's customers.
In some situations Mosese overbilled customers, which Mainfreight had to refund.
Woolley said offending could only be described as serious and the "sheer amount involved" and the fact it took place over seven years were aggravating factors.
It had a big impact on Mosese's former colleagues and flow on effects for the company's relationships with its customers, the Crown lawyer said.
Mosese was fired last August after the fraud was discovered. It came to light after Mosese was asked questions about outstanding credit owed by customers, with her answers arousing suspicion.
Despite stealing nearly $4.5 million over eight years, Mosese has few assets in New Zealand to show for her fraud.
Woolley said today that $3.2 million had been recovered from third parties after High Court civil proceedings and a subsequent settlement, leaving about $1.2 million owed by Mosese. Some funds from the sale of Mosese' family home and other assets may be used to pay this off, but around $1 million is still expected to be outstanding.
While Mosese's lawyer, Maria Mortimer, said the amount lost could be taken as $1.2 million, Woolley argued the loss caused by the offending was $4.4 million and that should be taken into account for the purposes of sentencing.
Mortimer said the offender was now left with nothing and her husband had moved to Australia.
Referring to a letter from the fraudster, Mortimer said the woman had worked for Mainfreight for more than 20 years, "enjoyed her job and loved everything about it".
Mortimer said her client's remorse was real and that she had a philanthropic background and had helped communities in her native country of Fiji.
Judge Cunningham, in sentencing Mosese, said reports provided by the Department of Corrections portrayed the offender as someone who like to show herself as a "successful and generous person".
The judge said Mosese also had two other businesses which she operated while working at Mainfreight and that "a good deal" of the stolen money went to them, often propping them up when they weren't viable.
The Crown wanted a sentencing starting point of six to seven years in prison, while the defence suggested a starting point of four to four and a half years.
The judge said she took into account that $3.2 million had been recovered when deciding on a starting point of six years in prison.
One aggravating feature, the judge said, was the length of the offending, which would have made uncovering the fraud more difficult.
Judge Cunningham said Mosese was not entitled to a discount for previous good character and that the woman had previous convictions in Fiji, involving theft from an employer.
The judge gave Mosese a 25 per cent discount for her guilty plea and sentenced her to four years six months in jail.