Abstract: A fastening device comprises a conical anchor piece (7, 17) and a conical recess (2) and, if necessary, an insertion piece (3). The conical outer surfaces (4, 10, 18) have annular grooves (5) on the one hand, and annular grooves (11) with O-rings or annular beads (19) on the other. The annular grooves (5) are somewhat offset in the height thereof with regard to the opposite annular grooves (11) or annular beads (9) so that in one anchor piece (7, 17), which rests with a stop, e.g. a flange (9, 20), a drawing force (14) serves to pretension. This results in the provision of self-tightening fastening device.

Abstract: A method is provided for the storage-efficient management of electronic messages, wherein a message that is to be managed is first received, the message is decomposed into a basic structure and file attachments contained in the message, a unique identification value is calculated for each file attachment, the file attachment is stored as a file with a respective identification value for which no file exists in the storage, or a reference counter of the file attachment for whose identification value a file already exists in the storage, is incremented, and the basic structure with references to the files in the storage, which references correspond to the file attachments originally contained in the message, is stored.