How to use CDO objects to send email with .mht file as attachment but not as Outlook file

I am using CDO as below, to email the output .mht file upon execution of project.

However my problem is that email is received with the attachment as output.mht.msg (Outlook item file) 

def SendEmail(mFrom, mTo, mSubject, mBody, mAttach):
    try:
        schema = "http://schemas.microsoft.com/cdo/configuration/"
        mConfig = Sys.OleObject["CDO.Configuration"]
        mConfig.Fields.Item[schema + "sendusing"] = 2 
        mConfig.Fields.Item[schema + "smtpserver"] = "something.com"
        mConfig.Fields.Item[schema + "smtpserverport"] = 25 
        mConfig.Fields.Update();
        mMessage = Sys.OleObject["CDO.Message"] 
        mMessage.Configuration = mConfig;
        mMessage.From = "someone@somewhere.com"
        mMessage.To = "anotherone@somewhere.com"
        mMessage.Subject = "Subject"
        mMessage.HTMLBody = "Body"
        mMessage.AddAttachment("file:///C:/Report.mht")
        mMessage.Send();
    except Exception as e:
        Log.Error("E-mail cannot be sent", str(e))
        return False
    Log.Message("Message was sent successfully to anotherone@somewhere.com")
    return True