An end-to-end encryption method for emails sent from a sender (1) to a recipient (6) is disclosed. According to the method, the sender requests from an encryption system (16) a certificate corresponding to the recipient (6), and the encryption system (16) returns to the sender (11) a first, proforma certificate corresponding to the recipient (6). The sender (1) sends with his email client (11) an outgoing email to the recipient encrypted with the proforma certificate, and the email is forwarded through the encryption system (16). The encryption system (16) decrypts the email using a private key corresponding to the certificate and also makes the content of the email available to the recipient (6).