The big four banks have identified customers sending “potentially offensive” messages in bank transaction descriptions.

Its new acceptable use policy states that it is unacceptable to use digital banking services to stalk, harass or intimidate anyone using the bank’s services.

Any customer found to be using NetBank or the CommBank app to engage in illegal, defamatory, harassing or threatening behaviour, promoting or encouraging physical or mental harm or violence against any person may have their transactions refused or access to digital banking services be suspended or terminated.

Catherine Fitzpatrick, general manager of community and customer vulnerability, said that over a three-month period the bank had identified more than 8,000 customers who had received multiple low-value deposits, often under $1, with potentially abusive messages. Abusers used the transaction descriptions effectively as a "messaging service," she said.

The bank made the finding as part of an analysis after noticing disturbing messages sent to a customer who had experienced domestic violence.

"We were horrified by both the scale and the nature of what we found," Ms Fitzpatrick said.

"All genders sent and received these messages, but the nature varied from fairly harmless banter using profanity to serious threats and clear references to domestic and family violence."

She added that the bank worked with experts, community partners and law enforcement to develop responses. The CBA uses the eSafety Commissioner's Safety by Design framework for guidance, a government initiative encouraging businesses to be proactive in considering user safety when developing online products and services.

The bank has also shared its findings with other banks and financial services organizations to ensure the issue is known in the industry.

Anna Bligh, chief executive of the Australian Banking Association, said CBA had done its customers a "great service" in identifying the abuse and taking action to stop it.

About one in four women and one in 13 men in Australia have experienced intimate partner violence, according to the 2016 ABS Personal Safety Survey.

Among women seeking support from domestic violence services, up to 90 percent are also affected by financial abuse.

"The message is simple, we can see you and we will not tolerate the use of our digital banking platforms to facilitate abuse," Ms Fitzpatrick said.

“Our customers should always feel safe using digital banking. These changes will ensure that all customers can continue to enjoy the benefits of digital banking in a safe and secure way [represent] our first step in addressing the problem of technologically facilitated abuse.

Sarah Simpkins

Sarah Simpkins is a journalist at Momentum Media, reporting mainly on banking, financial services and wealth.

Prior to joining the team in 2018, Sarah worked in commercial media and produced stories for a current affairs program on public radio.

You can contact her at [email protected].