A method of certifying transmission, reception and authenticity of electronic documents between a sender user (2) and addressee user (3) belonging to a telecommunication network (4) is disclosed, wherein the sender (2) carries out the following steps: drafting the document to be sent putting the electronic address of addressee (3), sending to a mailbox belonging to the telecommunication network associated to the addressee (3) a message comprising the drafted documents and wherein the addressee (3) carries out the step of downloading the message from the mailbox associated to him. The method provides for the automatic generation of a certificate of transmittal of the message that is being automatically sent to the mailbox of the sender (2) by a certification entity connected to the network when the message reaches the mailbox of the addressee (3).