Hello Recently we have switched over to a new ISP hence the public ip got changed. Few of my clients complain that they are unable to send email to our exchange server as they are getting bounce back messages.My exchange is getting mails it is not completely stopped. say a clients domain is abc.com, one user of abc.com is able to send email to my exchange and another user of abc.com domain is getting bounce back message. i have checked dns at isp its no issue and i can see MX, nslookup records pointing correctly to publicip. i use mcafee groupshield and i have stopped all its services.and it has been more than 10 days that we have switched over to new isp. similar issue with other clients of other domains. please guide me to troubleshoot this issue bounce back message from one client Subject: Delivery Status Notification (Failure) The following message to was undeliverable. The reason for the problem: 5.1.2 - Bad destination host "DNS Hard Error looking up mydomain.com' (MX): NXDomain" Test TEST TEST i checked ISP there is no issue MX record, MX record is correctly pointing.

On Mon, 28 Nov 2011 16:27:44 +0000, Risingflight wrote: >Hello Recently we have switched over to a new ISP hence the public ip got changed. Few of my clients complain that they are unable to send email to our exchange server as they are getting bounce back messages.My exchange is getting mails it is not completely stopped. say a clients domain is abc.com, one user of abc.com is able to send email to my exchange and another user of abc.com domain is getting bounce back message. i have checked dns at isp its no issue and i can see MX, nslookup records pointing correctly to publicip. i use mcafee groupshield and i have stopped all its services.and it has been more than 10 days that we have switched over to new isp. similar issue with other clients of other domains. please guide me to troubleshoot this issue bounce back message from one client Subject: Delivery Status Notification (Failure) The following message to was undeliverable. The reason for the problem: 5.1.2 - Bad destination host "DNS Hard Error looking up mydomain.com' (MX): >NXDomain" Test TEST TEST i checked ISP there is no issue MX record, MX record is correctly pointing. Perhaps the problem is at the sender's side? If you're asking for help with a DNS problem and you don't provide the domain name all you're going to get for answers are guesses. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP

On Mon, 28 Nov 2011 16:27:44 +0000, Risingflight wrote: >Hello Recently we have switched over to a new ISP hence the public ip got changed. Few of my clients complain that they are unable to send email to our exchange server as they are getting bounce back messages.My exchange is getting mails it is not completely stopped. say a clients domain is abc.com, one user of abc.com is able to send email to my exchange and another user of abc.com domain is getting bounce back message. i have checked dns at isp its no issue and i can see MX, nslookup records pointing correctly to publicip. i use mcafee groupshield and i have stopped all its services.and it has been more than 10 days that we have switched over to new isp. similar issue with other clients of other domains. please guide me to troubleshoot this issue bounce back message from one client Subject: Delivery Status Notification (Failure) The following message to was undeliverable. The reason for the problem: 5.1.2 - Bad destination host "DNS Hard Error looking up mydomain.com' (MX): >NXDomain" Test TEST TEST i checked ISP there is no issue MX record, MX record is correctly pointing. Perhaps the problem is at the sender's side? If you're asking for help with a DNS problem and you don't provide the domain name all you're going to get for answers are guesses. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP

Hi Risingflight, Please go to http://www.samdns.com/ to check the MX records for the domain. Please also go to https://www.testexchangeconnectivity.com/ to do a Inbound SMTP E-Mail. Frank