The Derbyshire (Isle of Man) is hoping to encourage its customers to use the service in preference to other banking methods, such as the telephone.
"For banks and building societies, whose customers want the ability to email account operating instructions both in the UK and abroad, this system provides secure encryption of the content and also a guarantee that the sender is who they purport to be," said Ken Bell, managing director of Quad Logic, which sold the solution to the bank.
The solution adopted uses encryption on customers' ordinary email packages. The recipient of email can then verify that it came from the sender's account.
Scams designed to hijack customer accounts, such as phishing attacks, are often targeted at the offshore market, said a spokesman for Quad Logic.