Bank Australia's pointed marketing is producing returns for the Melbourne-based mutual bank.Customer numbers increased by 10 per cent last year, while the bank's assets grew by 9 per cent to A$5.7 billion.Net profit lifted 11 per cent to $26.1 million."We are operating in an environment where there is a trust gap in banking, and an opportunity to put a responsible message there," managing director Damien Walsh said of its "The bank Australia needs" campaign.This campaign, Walsh said, "has seen shift to younger customers joining the bank with the average age of new customers at 39 years."Customer satisfaction, on Roy Morgan Research's measure, stands at 91 per cent.The bank is leaning hard on its environmental credentials, with four per cent of profits allocated to its "Impact Fund", multi-property, 927 hectare "Conservation Reserve", and structuring its first ever medium-term note as a "sustainability bond."Walsh said the bank was "not capital constrained at this point" and would consider opportunities to make use of upcoming law reforms on mutual capital over the medium term.