To provide a secure, effective but simple message handling, a method is provided for transmitting an electrical message, from a first user having a first terminal to a second user having a second terminal. The method comprises the steps of: transmitting said email in an encrypted form by said first terminal, said encrypted e-mail being encrypted by means of a key generated by a first key generator using a seed, providing once said second user with said seed for generating a key with a second key generator provided in said second terminal, providing to and storing said seed in said second terminal, using said seed by said second terminal for generating a key each time an encrypted email from said first user to said second user is received, synchronizing a counting value in each terminal; and generating said key on the basis of said seed and a counting value in each terminal, independently of other terminal.