  SPAWN, Terminal with Associated Mailbox? (TRMMBX) 
 The Question is:
 
When calling LIB$SPAWN I am receiving the following error:
%CLI-F-TRMMBX, terminal has associated mailbox - terminate image and then SPAWN
 
What does this mean and what do I do to cure it.
 
 
 The Answer is:
 
  The application running within the process context has declared
  a associated mailbox.  This is incompatible with the requirements
  of the SPAWN operation.
 
  One common cause of this error is an attempt to mix the use of SMG
  and lib$spawn.  SMG uses an associated a mailbox for notification
  of unsolicited keystrokes.  The SPAWN operation will not succeed
  when the associated mailbox is present, so you will want to use
  smg$create_subprocess or potentially use smg$disable_unsolicited_input
  and smg$enable_unsolicited_input around the lib$spawn call.
 
  The OpenVMS I/O User's Reference Manual chapter on the terminal driver
  describes the operation of associated mailboxes in some detail, and
  the typical interactions involved with their use.
 
 
$ HELP/MESSAGE TRMMBX
 
 TRMMBX,  terminal has associated mailbox - terminate image and then
          SPAWN
 
  Facility:     CLI, Command Language Interpreter (DCL)
 
  Explanation:  A SPAWN command failed because the current image has
                associated a mailbox with the terminal.
 
  User Action:  Terminate the current image, then reenter the command.
 
