set dont-print-headers

SET DONT-PRINT-HEADERS [fields]  -  define header fields to be hidden

The DONT-PRINT-HEADERS variable defines one or more header fields that
  should not appear when you use the PRINT or LIST commands.  

The commands LITERAL PRINT and LITERAL LIST ignore this variable.

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

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

Example:
    MM>set dont-print-headers received, return-path, message-ID

  You probably don't need the clutter of those fields on your printouts.

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