One of our client send the email to us,when he sent the email we recevied it,but on second time he sent the email he get the below NDR. Thu Oct 28 08:52:53 2010 Info: New SMTP DCID 131361455 interface xxx.xxx.xxx.xx address xxx.xxx.xxx.xxx port 25 Thu Oct 28 08:52:53 2010 Info: Delivery start DCID 131361455 MID 381741891 to RID [0] Thu Oct 28 08:53:00 2010 Info: Bounced: DCID 131361455 MID 381741891 to RID 0 - 5.1.0 - Unknown address error ('554', ['5.1.0 Sender Denied']) Thu Oct 28 08:53:06 2010 Info: DCID 131361455 close and also want to now problem lies to my end our client end Please provide me solution.

Its clearly saying that sender SMTP server IP address is denied by your SMTP sevrer (- 5.1.0 - Unknown address error ('554', ['5.1.0 Sender Denied']) Two option to fix this issue: 1: Ask sender to change IP of SMTP server if he has this complain from other domain also 2: white list sender SMTP domain in spam databse.Anil