Email not received in correct format

 Hi Guys,

I am sending email from my oracle 11.1.0.6 database with an attachment. The attachment I receive it comes as in unknown format however I can open this file by saving on local disk using wordpad or MS Excel but I can't double click it.

Also the file is saved in correct CSV format on my linux box and it is readable.

Following is my code:

/* This procedure will generate the report and drop the file on linux box */

CREATE OR REPLACE PROCEDURE pr_dailySalesReport
AS
    l_length          NUMBER;
    l_line             CLOB;

    l_fileid          UTL_FILE.file_type;
    l_maxlinesize     BINARY_INTEGER := 32000;