The 'New' button on the MacroView DMF file list toolbar displays the each of the document and folder content types in the selected library.
Options to create folders, documents sets and new Office documents based on templates on you local PC may or may no be shown depending on your DMF options to display these items. See Create folders and documents from the File List Toolbar for more information.
If you want to change the template associated with a particular content type, for example to have the Email content type initiate a new email message, open the library settings in the browser, select the content type then Advanced Settings.
Then either clear or upload a different template for that content type.
Note: For emails you should create a blank or template email and saved it as a .oft file.