I'm facing a problem that Exchange is not sending and receving any emails. it seems there an spamming issues.The message keeps on tryig but never gets delivered.the LAst Error Colums shows - 451 4.4.0 DNS Query Failed451 4.4.0 Primary target ip ddress responded with 421 4.4.2 Connection dropped451 4.4.0 Primary target ip ddress responded with 421 4.2.1 unable to connect

Hi,What is the version of Exchange and OS ?Try running nslookup test and check whether you are able to resolve the DNS.nslookup -q=mx domain.com (the problematic domain)_________Sanjay

Is that an outgoing message? If so it could be that the recipient's server is dropping you because of something like a bad or nonexistent reverse lookup PTR DNS record for you.-- Ed Crowley MVP"There are seldom good technological solutions to behavioral problems.". "Vministrator" wrote in message news:b05ad626-5646-4fa4-86a5-9efba36a23fb...I'm facing a problem that Exchange is not sending and receving any emails. it seems there an spamming issues.The message keeps on tryig but never gets delivered.the LAst Error Colums shows - 451 4.4.0 DNS Query Failed451 4.4.0 Primary target ip ddress responded with 421 4.4.2 Connection dropped451 4.4.0 Primary target ip ddress responded with 421 4.2.1 unable to connect Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hi,What version of Exchnage and OS are you using.Mahendra

Exchange 2007 SP2 running on Windows Server 2003

even it not deliveing the messages to the user within the domain

i've recieved few of the emails now which i've sent in the last 12 hrs.

Hi,Do you see any erorrs in the event log?Mahendra

Event Type: WarningEvent Source: MSExchangeTransportEvent Category: ResourceManager Event ID: 15004Date: 3/9/2010Time: 2:25:14 AMUser: N/AComputer: EAI-MAILDescription:Resource pressure increased from Normal to High. Resource utilization of the following resources exceed the normal level:Version buckets = 109 [High] [Normal=40 Medium=60 High=100]Physical memory load = 96% [limit is 94% before message dehydration occurs.] Back pressure caused the following components to be disabled:Inbound mail submission from Hub Transport serversInbound mail submission from the InternetMail submission from the Pickup directoryMail submission from the Replay directoryMail submission from Mailbox serversMail delivery to remote domains The following resources are in the normal state:Queue database and disk space ("G:\Program Files\Microsoft\Exchange Server\Transportroles\data\queue\mail.que") = 89% [Normal] [Normal=95% Medium=97% High=99%]Queue database logging disk space ("G:\Program Files\Microsoft\Exchange Server\Transportroles\data\queue\") = 89% [Normal] [Normal=95% Medium=97% High=99%]Private bytes = 63% [Normal] [Normal=71% Medium=73% High=75%] For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Hi,It seems that back pressure was aplied to your system due to insiffucient resources.Please check the below article for detailshttp://technet.microsoft.com/en-us/library/bb201658(EXCHG.80).aspxPlease check which resource is facing issue in your setup.Mahendra

now there is no back pressure but still the same issue. internal emaila are working buy no sending outside.

Hi, Can you check if there is any issue on your DNS server used for resolution of address. Are you able to query the DNS server from your exchange? Mahendra

DNS is all set

exchange is all set now and sending /receving the emails.

Could you share what fixed the issue?Mahendra