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

    Specifies that the last message you sent will be used as text
    for the message you are currently sending. You can use the /LAST
    qualifier with the /EDIT qualifier to edit the message before
    sending it.