I am seeing considerable latency delivering messages to a dynamic DL that sends to all the mailboxes in my orginization, about 9,300 mailboxes. I have two message tracking log files both from the same day, both sending from the same user to the Dynamic DL. One delivery took about 3 minutes, and the other took just under 30 minutes. Below is part of the message tracking log.Notice over 25 minutes between the first and second timestamp?Timestamp : 9/9/2009 9:25:25 AMClientIp : fe80::59c5:fb88:f1fb:69d6ClientHostname : MS-EXCH-CCR02.xxx.xxx.xxxServerIp : fe80::XXXXXXXXXServerHostname : MSxxxSourceContext : ConnectorId : Source : STOREDRIVEREventId : RECEIVEInternalMessageId : 2009468MessageId : <B3B9A3921489E64EAAB015F8CA6D082A464CDCC67E@.xxx.xxx.xxx>Recipients : {Messenger@xxx.xxx.xxx, AllUsers@xxx.xxx.xxx}RecipientStatus : {}TotalBytes : 5274RecipientCount : 2RelatedRecipientAddress : Reference : MessageSubject : Employee SendSender : Messenger@xxx.xxx.xxxReturnPath : Messenger@xxx.xxx.xxxMessageInfo : 04I: Timestamp : 9/9/2009 9:49:04 AMClientIp : ClientHostname : ServerIp : ServerHostname : MSxxxSourceContext : ADxx.xxx.xxx.xxxConnectorId : Source : ROUTINGEventId : EXPAND Any ideas Why such a delay?

Did the DL expansion use the same HT servers? ( the 1st quick mesage versus the 2nd slow one? )What time was the 1st quick one sent?

They both used the same HT server. But, they did use different DC's. We are single forest, single domain.the slow one was sent at 9:30 am and the fast one was sent at 3:30 pm. Both on the same day

But, they did use different DC's.Then please try to verify if the DCs are in the same status.Please try to force DC to replic with each other.Besides,please try to run ExBPA to have a health scan to see if any DC related error will be logged in the report.Regards,Xiu

Please run dcdiag and netdiag from exchange box and make sure the DC and GC's are in sych. http://technet.microsoft.com/en-us/library/cc783438%28WS.10%29.aspx http://technet.microsoft.com/en-us/library/cc776854%28WS.10%29.aspx Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Thank you, I will try the suggestions above this morning and report back.I did find out that this is a known bug in E12. Bug number is 134361We are on SP1, RU8. Trying to determineif RU9, or SP2 will address this issue?

Hi,Bug 134361 has no plan to fix. So far there's no hotfix for this bug Besides, we have a KB pending for bug 161628(kb951000),but it is still in progress. Since the issue addressing about 9300 mailboxes, I recommend you to call PSS to get better help. Select a Product Solution Center http://support.microsoft.com/select/?target=hub Regards, Xiu