Hello,some Users were unable to send/receive emails to/from external addresses in my organization. This outage lasted for around 5 hours.I need to provide the details about to Problem Management: 1. Workaround applied to solve this problem2. Root cause3. PreventionHow can I provide that..?

Well, first off, have you fixed the problem? If so how did you fix it? This gives you the content for parts 1 and 2.It will also help you find the content for 3Things to look for.1) patterns of the users that had the issue..Same server? same office/location? particualr addresses?2) NDRs. look for any data and reasons in the NDRs for the fault.3) Event logs. check servers and clients

All right thank you.I would like to know how do you fix the problem in general? when a user is unable to send/receive emails to/from external addresses?

Well, if the internal mail is OK, then the problem lies with either your Send Connectors, your internet connection or your ISPs DNS servers. Testing for this is extensive, but can be bolied down into simple sections.Check internet connectivity. If that works then it could beaddressing or Send ConnectorsUse an external mail program (hotmail, yahoo mail, gmail, etc, etc) to send a test to yourself or the external recipent who you can't send or receive fromCheck your send connectors. ensure that the address space is configured correctly and that the connector sends mail to that space to a vaild server.Check its not the client by telnetting to your server on port 25 and sending mail that way. There is documentation on this and I will post it as soon as I find it.Generally, fault diagnosing Exchange is a BIG subject especially with no information from the undeliverable mail.

Do you have any NDR messages? -- Petri

Hi, I would like to explain that we need to gather more information to troubleshoot the issue: 1. We need to separate the message send and receive issue 2. We need to gather the NDR message to check the possible cause of the issue 3. We need to gather Message Tracking log to check where the issue occurs 4. Sometimes, we also need to check SMTP Protocol log, event logs, capture Network Package and other information in order to locate the root cause of the issue. Therefore, for your issue, I suggest you focus on the message send issue, please let me know: 1. Whether the issue only occurs when sending to specific external recipients or all external recipients 2. Whether any NDR message or error message is received? If yes, please post the information here 3. Which type of client is used to submit message to Exchange Server? SMTP or MAPI 4. Please let me know your outbound mailflow. Some information may help you troubleshoot the issue: Non-Delivery Report Issues http://technet.microsoft.com/en-us/library/bb397219.aspx Mike