"To" field is blank in the email sent from SMTP

We have a requirement to send email from loadrunner.

For the below code if I send the email, the "To" field is blank in the email.

    smtp_send_mail("SendMail",
        "To=receiver@abc.com",
        "Subject={Subject}",
        "From=sender@tbc.com",
        "ContentType=text/plain;",        
        "ContentType=application/pdf;", 
        "ContentType=multipart/mixed;",        
        "ContentDisposition=attachment;",
        "filename={P_Attachment}",
        "charset=\"iso–8859–4\"", 
        MAILOPTIONS, 
            "X–Priority: 3", 
            "X–MSMail–Priority: Normal", 
            "X–Mailer: Microsoft Outlook Express 10.31.112.206", 
            "X–MieOLE: Produced By Microsoft MimeOLE V5.00.2919.6700", 
        MAILDATA,
            "AttachFile={P_Attachment}",
        LAST );