SMTP Server Issue in intersystem cache

I am facing an issue when I am sending Email from intersystems cache. I am able to send the mail, with out any problem the first time. But the second time when I am trying to send the smtp server is not responding properly. The first Helo command is sent. I recieve the confirmation 220 from the server. But I do not recieve the Message 250. So the next command is giving me the erro开发者_如何学Pythonr 503, 5.5.2 "Send helo first" message.

I am unable to find out why the server is not responding the second time.