MIME types can be associated with an external program to be viewed. This is done in the database with the programs
table.
File extensions may be associated to programs through the operating system. When an attached file has an extension registered in the system, the contextual menu on that attachment has an
entry. Also when double-clicking on the attachment, an choice is proposed in a intermediate dialog box. Currently, this association between file extensions and programs is only checked on the Windows platform.