z

Z (same as SUSPEND)  -  suspend MM

Usage:  Z
   or:  control-z

The Z or SUSPEND command leaves MM and suspends the process.  This is the 
  only way to leave MM directly from READ MODE.  Z does not rewrite the 
  mail file first if there were only minor changes.

Continue the process later by typing either "fg", if MM was the last process
  you suspended, or "mm", which, in our standard environment, means 
  "fg -s /usr/local/bin/mm" (see /etc/kshenv1).

Example:
  Read>z 				
  [1] + Stopped (signal)  /usr/local/bin/mm
  $ fg                                          #or "mm"
  /usr/local/bin/mm
  Read>

For more help type "help" and one of these topics:
  suspend   basic   push   shell   top-level-mode quit