The invention relates to a system comprising: a first computerized system, or emitter, connected to a communication network; a second computerized system, or receiver, connected to said network; and a server connected to said network. Said server operates as a trusted third party for electronic transactions, is adapted in such a way as to offer a custody service and to vouch for the existence and content of an electronic document sent by the emitter, and communicates with a timestamping entity.The invention also relates to a method according to which the system is used to send a notification and/or contracting request for a receiver and an associated electronic document, from an emitter to said server, and to allow the receiver to securely access said document stored in a repository of the server, the transaction executed being traceable from beginning to end, and repudiation in the origin and destination avoided.