set only-print-headers

SET ONLY-PRINT-HEADERS [fields]  -  define header fields to be shown

The ONLY-PRINT-HEADERS variable defines one or more header fields as the
  only ones that should appear when you use the PRINT or LIST commands.  

The commands LITERAL PRINT and LITERAL LIST ignore this variable.

To unset it, type SET ONLY-PRINT-HEADERS with nothing following.

ONLY-PRINT-HEADERS overrides the variable DONT-PRINT-HEADERS.

Example:
    MM>set only-print-headers date, from, subject
  You might do this before a PRINTing or LISTing a set of messages, to
  reduce the space taken up by headers you aren't interested in.

For more help, type "help" and one of the following:
(at any prompt:)  save-init   set   show   print   list   literal
                  set dont-print-headers
                  set only-type-headers   set dont-type-headers