Method of secure transmission using a fax server, comprising the following steps: - a step of transmitting, by an emitter, to a server the document to be faxed, in the form of a digital file with a non-fax format, as well as information concerning the identity of the addressee; - a step of calculating on the one hand a file in TIFF format using said digital file supplemented with a standardised information page and on the other hand the date and time said TIFF file was created; - a step of encapsulating said timestamped TIFF file in a file in a format suitable for reading with a standard editor such as the PDF format; - a step of calculating a signature using said timestamped then encapsulated TIFF file and of registering the result of this calculation in a complementary file; - the recording of said timestamped then encapsulated TIFF file and of said complementary file in a secure space that can be accessed by the emitter and the addressee; - the modification of said timestamped TIFF file to be transmitted in order to insert therein on said standardised information page said signature, the fax number of the addressee and a password calculated by the server allowing the addressee to access said saved timestamped then encapsulated TIFF file and said complementary file; - the transmission by the server to the telephone address of the addressee of said timestamped then modified TIFF file, according to a fax standard; - the emitting by the server of a transmission report in the form of an electronic message with a non-fax format; - in case of the verification of the authenticity of a reference file that a user has and of a presumed signature that corresponds to the reference file, a step of transmitting to the server said reference file that the user has and the presumed signature and a step of returning by the server of a response for confirmation or information on the authenticity of said reference file and of the associated signature. - a step of transmitting, by an emitter, to a server the document to be faxed, in the form of a digital file with a non-fax format, as well as information concerning the identity of the addressee; - a step of calculating on the one hand a file in TIFF format using said digital file supplemented with a standardised information page and on the other hand the date and time said TIFF file was created; - a step of encapsulating said timestamped TIFF file in a file in a format suitable for reading with a standard editor such as the PDF format; - a step of calculating a signature using said timestamped then encapsulated TIFF file and of registering the result of this calculation in a complementary file; - the recording of said timestamped then encapsulated TIFF file and of said complementary file in a secure space that can be accessed by the emitter and the addressee; - the modification of said timestamped TIFF file to be transmitted in order to insert therein on said standardised information page said signature, the fax number of the addressee and a password calculated by the server allowing the addressee to access said saved timestamped then encapsulated TIFF file and said complementary file; - the transmission by the server to the telephone address of the addressee of said timestamped then modified TIFF file, according to a fax standard; - the emitting by the server of a transmission report in the form of an electronic message with a non-fax format; - in case of the verification of the authenticity of a reference file that a user has and of a presumed signature that corresponds to the reference file, a step of transmitting to the server said reference file that the user has and the presumed signature and a step of returning by the server of a response for confirmation or information on the authenticity of said reference file and of the associated signature.