/sys$common/syshlp/helplib.hlb MAIL Command, Qualifiers, /EDIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /EDIT[=(keyword[=option], . . . )]

    Sets the default to /EDIT for the SEND and REPLY commands and
    allows you to edit your mail messages. By default, the DECTPU-
    based EVE editor will be invoked. You can use the SET EDITOR
    command in MAIL to change your editor.

    Valid keywords are FORWARD, REPLY[=EXTRACT], and SEND.