VMS Help MAIL Routines, MAIL$MESSAGE_SELECT, Condition Values Returned  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    MAIL$_ILLCTXADR    The context block address is illegal.
    MAIL$_INVITMCOD    The specified item code is invalid.
    MAIL$_INVITMLEN    The specified item length is invalid.
    MAIL$_INVQUAVAL    The specified qualifier is invalid
    MAIL$_MISREQITEM   The required item is missing.
    MAIL$_NOFILEOPEN   The mail file is not open.
    MAIL$_NOTEXIST     The specified folder does not exist.
    MAIL$_NOTISAM      The operation applies only to indexed files.
    MAIL$_WRONGCTX     The context block is incorrect.
    MAIL$_WRONGFILE    The specified file is incorrect in this
                       context.
    SS$_ACCVIO         Access violation.
    Any condition value returned by LIB$GET_VM.