VM uses Emacs’ menu bar and pop-up menus whenever they are available
using which you can readily access VM’s commands.  By default, VM puts
a context-sensitive pop-up menu on mouse button 3 (usually the
rightmost mouse button).  If you don’t want this menu, set the
variable vm-popup-menu-on-mouse-3 to nil.
If you set vm-use-menus to nil, VM will not generate a menu bar
for VM folder buffers and VM won’t use pop-up menus either.  If you
set vm-use-menus to ‘1’, VM will add a single ‘VM’
menu to the existing menu bar and provide various submenus under it
for the VM operations.
By default, vm-use-menus is set to a list of symbols indicating
which menus should appear in the menu bar.  These menus will replace
the standard Emacs menus whenever VM folder are being viewed.  You can
switch to the Emacs menu bar when necessary by clicking on the menu
labelled [Emacs] (on some systems, thre will be a drop-down
menu labelled Emacs).  From the Emacs menu bar, you can return
to the VM menu bar by clicking on the menu labelled [VM] (or
under the drop-down menu labelled VM).
On some graphics toolkits, menu bar cannot have “buttons” that
invoke immediate actions (such as [Emacs]).  VM knows about
some of those toolkits and automatically uses drop-down menus instead
of buttons.  If your system shows buttons but they are not
operational, then you should set vm-use-menubar-buttons to nil
in your init file.  That will cause VM use to drop-down menus instead
of buttons on the menu bar.
The available menus for the VM menubar are the following:
disposeThis is menu of commands that are commonly used to dispose of a message. E.g. reply, print, save, delete.
emacsThis provides a menu button labelled [Emacs] that causes the
menu bar to change to the global Emacs menu bar.  On that menu bar you
will find a [VM] button that can return you to the VM menu
bar.
folderThis is a menu of folder related commands. You can visit a folder, save a folder, quit a folder and so on.
helpThis is a menu of commands that provide information for you if you don’t know what to do next.
labelThis is a menu of commands that let you add and remove message labels from messages.
markThis is a menu of commands that you can use to mark and unmark messages based on various criteria. See Marking Messages.
motionThis is a menu of commands to move around inside messages and inside folders.
sendThis is a menu of commands you use to compose and send messages.
sortThis is a menu of commands to sort a folder by various criteria.
undoThis provides a menu button that invokes the vm-undo command.
virtualThis is a menu of commands that let you visit and create virtual folders.
nilIf nil appears in the list, it should appear exactly once. All menus after nil in the list will be displayed flushright in the menu bar.