关闭传输错误。超时等待来自客户端的数据

I am using local host to send bulk mails through SES. This question is answered by many but none of the solutions is helping me. The problem is I could send 100/ 150 mails at a time after that the above error is showing up. I tried to dispose of the client as suggested by some, but not working. I am using C# code to do this. Any answers/ suggestions is much appreciated. The below is the code I am using to send bulk mail using for loop. You might be thinking it might be a throttling issue, it is not because we have 70 emails/second and 500000 emails per day.I am using local host to send bulk mails throug