Hi,Recently i have installed an Exchange Server 2007 and all the role (Mailbox, CAS, and Hub Transport) installed on one server. All the mails route from Exchange to Remote SMTP Connector(Upstream Organisation).Everything is working fine. Only when some users send an email outside of the organisation to more than one recipient(Group of users), the message will be in the queue for a long time. The error message in Queue next to the message i get is: "421 4.4.2 connection dropped".After one day the message will be sent. also when i restarted the exchange 2007 then i did not get any message in RemoteSMTPConnector Queue.Does anyone assist me why this is happening? Please.....Some tips or hints will be very appreciated!

Hi Mahtab, Please help gathering the following information for further research: 1. Increase the Transport Diagnostic Level, repro the issue and gather related event log Note: Please post the entire log here. You can increase Transport Diagnostic Level by modify the data to 7 of the following registry key values: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeTransport\Diagnostics 2. Please enable the SMTP Protocol log on the send connector and the connectivity log on the Exchange Server. Then, repro the issue and post the result here You can refer to the following article to configure the logs: http://technet.microsoft.com/en-us/library/aa996827(EXCHG.80).aspx http://technet.microsoft.com/en-us/library/bb124531(EXCHG.80).aspx In addition, please let me know whether the specific users always encountered the problem when sending email to several external recipients. Whether the users send to a group which include serveral external recipients or to serveral recipients directly. Mike