FFVIEWER has the optional command-line switches as shown below.

In all cases the mailbox filename, when used, should be specified in the format: 12345678.MBX.

-m mbxnameThis switch causes FFVIEWER to start up with the Mail Selection dialog active, and automatically restores this dialog after the current document has been cleared with the Escape key or after the document has been moved with the Move/Copy dialog or has been deleted using the Action menu or the DEL key.  If the mbxname mailbox filename is added, this mailbox is used as the initial mailbox in the selection dialog.
-n mbxnameThis switch is the same as the -m switch except that it disables the combobox used to select a mailbox on the Mail Selection dialog.
-s mbxnameThis switch is the same as the -m switch except that the folder specified in the mailbox is re-scanned every two minutes when the application is idle, and the viewer is made active if there are unviewed files.  The mailbox name is required.
-a mbxnameThis switch makes the viewer operate in 'approval mode'.  It is the same as the -m switch except that the folder specified in the mailbox is re-scanned every two minutes when the application is idle, and the viewer is made active if there are unprocessed files. The mailbox name is required unless only outbound files are to be approved.