Today I had a very strange problem with mail floating. Messages sent to one distribution group were stuckung in a queue SMTP Relay to Local AD SITE. The last error was: "451 5.7.3 cannot achieve exchange server authentication". Any other mail floated well this time.I did not change anything, but some time later the problem has disappered. I have two Hub Transport servers and SCC Mailbox Server. The messages were hanging on one of transport servers.This is trackung of one of hanged letters:Timestamp EventID Source SourceContext Recipients2008/10/08 12:15:46 RECEIVE STOREDRIVER groupname@domain.com2008/10/08 12:15:46 TRANSFER ROUTING Resolver groupname@domain.com2008/10/08 12:43:38 EXPAND ROUTING dc00.domain.com member1@domain.com2008/10/08 12:43:38 TRANSFER ROUTING ContentConversion member2@domain.comYou can see that the delay was about half of hour.What was that?

Hi, Whether the two Hub Transport servers locate in different AD site? Whether the Edge server was deployed there? Whether the Distribution group is the new group that was created just now? Please run get-receiveconnector |fl on the Hub Transport servers, then post the information on the forum. Thanks Allen

Both of Hub transport servers are in a same site. There are no Edge server. This group contains users located in one site. The group was created a long time ago and it was used oftern. There are a lot of receive connectors for the different needs on servers. Which one do you want to see? I dont think the problem is because of connectors, because it was solved by itself. Allen Song - MSFT wrote: Hi, Whether the two Hub Transport servers locate in different AD site? Whether the Edge server was deployed there? Whether the Distribution group is the new group that was created just now? Please run get-receiveconnector |fl on the Hub Transport servers, then post the information on the forum. Thanks Allen

Hi, I understand that the connector is out of use in process of sending internal email. Now please run get-mailboxserver |fl command in EMS, let me know the outcome that is displayed. Thanks Allen

Allen Song - MSFT wrote: I understand that the connector is out of use in process of sending internal email. Now please run get-mailboxserver |fl command in EMS, let me know the outcome that is displayed. The names of domain and servers are changed due to security reasons. Name : exchange_sccManagedFolderAssistantSchedule : {.0:00-.9:00, .0:00-.9:00, .0:00-.9:00, .0:00-.9:00, .0: 00-.9:00}LogPathForManagedFolders : C:\Program Files\Microsoft\Exchange S erver\Logging\Managed Folder Assistan tLogFileAgeLimitForManagedFolders : 00:00:00LogDirectorySizeLimitForManagedFolders : unlimitedLogFileSizeLimitForManagedFolders : 10MBMessageTrackingLogEnabled : TrueMessageTrackingLogMaxAge : 30.00:00:00MessageTrackingLogMaxDirectorySize : 250MBMessageTrackingLogMaxFileSize : 10MBMessageTrackingLogPath : C:\Program Files\Microsoft\Exchange S erver\TransportRoles\Logs\MessageTrac kingMessageTrackingLogSubjectLoggingEnabled : TrueMAPIEncryptionRequired : FalseRetentionLogForManagedFoldersEnabled : FalseJournalingLogForManagedFoldersEnabled : FalseFolderLogForManagedFoldersEnabled : FalseSubjectLogForManagedFoldersEnabled : FalseSubmissionServerOverrideList : {}ClusteredStorageType : SharedAutoDatabaseMountDial : LosslessForcedDatabaseMountAfter : unlimitedRedundantMachines : {exch00, exch01}ReplicationNetworks : PrivateThenMixedIsPhoneticSupportEnabled : FalseLocale : {}IsValid : TrueOriginatingServer : dc01.domain.comExchangeVersion : 0.1 (8.0.535.0)DistinguishedName : CN=exchange_scc,CN=Servers,CN=Exchange Administrative Group (FYDIBOHF23SPDL T),CN=Administrative Groups,CN=xxxxxxx,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=domain,DC=comIdentity : exchange_sccGuid : 8bbb4e6f-5605-4cf6-8489-d5b2b58e8c57ObjectCategory : domain.com/Configuration/Schema/ms-Exch-Exchange-ServerObjectClass : {top, server, msExchExchangeServer}WhenChanged : 05.08.2008 18:04:03WhenCreated : 11.07.2008 15:31:41

Hi, After viewing the information, I didn't abnormal symptom. Now please locate Distribution Group in EMC, double click the DL, in the Advanced tab, please check the settings of the Expansion server. Is it Any sesrver in the organization? You can also specify one of the Hub Transport server to check this issue. Please restart Microsoft Exchange Transport server. Thanks Allen

The expansion server was Exch00, I have changed it to ANY when this problem occured. Now I came to server Exch00 and saw that it is in a strange state. All services are started and there are no errors in event logs, but it does not recieve any messages. After restarting Microsoft Exchange Transport Server Service, server became a normal state. Do you think the problem was because of that?

Hi, Please understand that Exchange Transport service encapsulates all of the core components, such as categorization, routing, and remote delivery. Obviously, the message hung the phase of routing that was related to Exchange Transport service. We can monitor this issue for some time and verify whether such issue will reoccur. If still encountered, please specify the other Hub Transport server as the expansion server. Thanks Allen

I have this problem again. The local mail goes with a 30-40 mins delay. Here is a message from SCOM 2007:Largest Delivery Queue Length - sustained for 5 minutes - Yellow(>200) - Hub Transport.Source: fe00Path: fe00.domain.comLast modified by: SystemLast modified time: 30.10.2008 15:54:19Alert description: MSExchangeTransport Queues: Largest Delivery Queue Length: _totalvalue = 210.19999999999999It looks like my mailbox server did not accept messages from my hub transport server for some time. In a tracking of hub transport I see this:2008/10/30 15:52:41 RECEIVE STOREDRIVER <163CE060087E504A9BF02EE6D66277A707A21042FB@EXCHANGE.domain.com>2008/10/30 16:25:45 DELIVER STOREDRIVER <163CE060087E504A9BF02EE6D66277A707A21042FB@EXCHANGE.domain.com>How can I find why this happens?Here is a screen: