Exchange email queue stuck in message queue viewer with error “451.4.04 DNS query failed”
HI folks, Yesterday I was in office and one salse officer report one email issue. - he was send mail to one client id but that mail was not received by client. basicaly I told just give me a exact time and recipient details (Email ID) that officer reply me with all details. then I start my troubleshooting.. step by step.. 1) I was checked organization mails in/out working ... OK 2) opened mail tracking and provide all inpute for mail tracking... Oppps mail was not found in tracking log.. 3) Then I run to message queue viewer ... and i found for that domain mails queue are in retry status. I expand queue viewer and check what is last error. Error was - 451.4.04. DNS query failed Then I was checked MX records are resolving for that doamin. run the command prompt. > Nslookup >set q=mx > domain name.com {Enter} and result in attached snap.. . Booom I come to know that is issue happened due to mx record not resolving and query not fowordi