Initially Dr Mailer worked to develop canola quality rapeseed, for export markets, to compete in international canola markets. His study focused on factors responsible for quality characteristics including agronomic and environmental studies. Many publications on these issues here illustrate the role of nutrients, water and temperature stress on oilseed quality.

For a number of years he studied olive oil quality and production as the crop has developed into a significant Australian industry. His studies focused on how quality can be controlled. Irrigation, harvest timing, processing and storage have been the key factors in this research. He has worked to identify issues of fraud or adulteration in commercial olive oils both within Australia and internationally, particularly in the USA. He became accredited with the International Olive Council and utilized those methods to ensure that consumers can ensure what they buy, or sell, is indeed extra virgin olive oil.

Dr Mailer has played a key role in developing standards for edible oils for Australia and globally in his role as the Australian Technical representative on the International Standards Organisation, Codex Alimentarius and Standards Australia.

Dr Mailer developed reliable and rapid methodology which has contributed to developments in the canola and olive industries throughout Australia.