/ENCODING=encoding

    Specify the encoding method to use to encode an input message
    file. Typically, no encoding is used; however, this depends
    upon the file type as determined from the file extension. The
    available encoding methods are 7BIT, 8BIT, BASE32, BASE64,
    BINHEX, BTOA, COMPRESSED-BASE64, BASE85, HEXADECIMAL, PATHWORKS,
    QUOTED_PRINTABLE, UUENCODE, and COMPRESSED-UUENCODE.