utl_smtp application/pdf, pdf attached show as characters

    The code:

declare 

    v_bfile        BFILE;

     destoffset      INTEGER := 1;

     warning        INTEGER;

    v_length       INTEGER :=0; --T37250

    v_raw         RAW(57); --T37250

    v_buffer_size     INTEGER := 57; --T37250

    l_boundary      CONSTANT VARCHAR2(256) := '7D81B75CCC90D2974F7A1CBD'; --T37250

    first_boundary    CONSTANT VARCHAR2(256) := '--'|| l_boundary|| utl_tcp.crlf; --T37250

    last_boundary     CONSTANT VARCHAR2(256) := '--'|| l_boundary|| '--'|| utl_tcp.crlf; --T37250

    multipart_mime_type  CONSTANT VARCHAR2(256) := 'multipart/mixed; boundary="'|| l_boundary|| '"'; --T37250

    mailhost VARCHAR2(64) := 'smtp.email.us-ashburn-1.oci.oraclecloud.com';

   sender VARCHAR2(64) := 'picking@fasa.com.pa';

recipient VARCHAR2(64) := 'pablo.martinez@solusoft.com';

wallet_pwd VARCHAR2(64) := 'Manager1';

wallet_loc VARCHAR2(64) := 'file:/home/oracle/SMTP/';