A method for increasing the privacy of an e-mail message, comprises the steps of: a) providing a central Server (PS) which stores concordance tables between decryption key data and the different identification given to them by different users; b) at the Sender's terminal (ST), encrypting a message using an encryption key, and sending by e-mail the encrypted message to the Recipient (RIT); c) providing the RT with a Partial encryptionldecryption Key, which is the decryption key modified by a given Operator (OP); d) sending by the ST to said PS an Operator Identification (OI); belonging to ST, which identifies OP employed by ST to generate the encryption/decryption key, and which is obtained from the Operator Table stored at ST; e) at PS, obtaining OP from the Sender Operators Table stored at PS, using the OI; of ST sent to PS by ST; f) at PS, obtaining OI; of the RT, from the Recipient Operators Table stored at PS, using OP; g) sending to RT its OI, together with any additional data; b) at RT, receiving the encrypted message and the Partial Key from ST, and OI: from PS; i) extracting OP using the Operator Table stored at the RT, and generating therewith the decryption Key from the Partial Key; and j) decrypting the encrypted e-mail message.