You can use MAIL$SEND_ADD_BODYPART to specify a file that
    contains the entire message or to add a single record to a
    message. If the message is contained in a file, you call
    MAIL$SEND_ADD_BODYPART once, specifying the file name. If
    you want to add to the message record-by-record, you can call
    MAIL$SEND_ADD_BODYPART repeatedly, specifying a different record
    each time until you complete the message.

    You cannot specify both a file name and a record for the same
    message. You can specify either MAIL$_SEND_FILENAME or MAIL$_
    SEND_FID once, or you can specify MAIL$_SEND_RECORD one or more
    times.