Outlook cannot connect to Exchange Server

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  • Hello

    We have strange things going on here. We are running Exchange 2003 on SBS. Periodically the Outlook Clients break the connection to the Exchange Server. Ager some minutes and restrating Outlook the Clients can connect to the server again.

    Any ideas?

    Thank you for your Responses!

    Greetings, Marcel

  • Hi Marcel,

    does the error concern all or only one user?

    If it is only one user, you should examine the network configuration. The network map should not "auto" but on "half" or "full". Also you should examine the configuration of the SWITCH.

    If the error comes with all user, it can be that the server is overloaded and the RPC inquiries cannot processed.

    How is your server equipment? (CCU & RAM)
    How is the extent of utilization in the task manager?
    How many Users / Mailbox contain the server?

    Alternatively you could activate the Cache mode also with Outlook 2003. This minimizes the server load substantially!


  • Hi Heinz

    This error concern different users, not just one.

    Server Equipment:

    CPU: 3.2GHZ Perntium 4
    Ram: 2GB
    Users & Mailboxes: 12

    The CPU Usage is not that high, Ram is used a lot. Sometimes the page file shas to be used..

    The Caching Mode is activated on all clients.

    One, i had the problem, that i had not enough virtual memory, so i reseized the page file.

    Do you think, it's a hardware dependent problem?


    Greetings, Marcel

  • With 12 User ? I do not believe that!

    Whats about your networkkonfiguration?
    (Network card with ?full duplex? or ?half duplex?)

    Maybe a DNS problem. Add the Exchange server name and IP address in the local host file of your client.


  • Hello Heinz

    I did some "stress tests" with the server now. with that i wanted to force the outlook client to reproduce the problem. Didn't work, alle the RPC calls were answered from the server.

    It could be possible, that it has to do something with the DNS. We changed ISP some Weeks ago, since the the problem persists.. We changed IP's and FW Config etc..

    I checked the hosts files and added the hostname and Ip of the Exchange server. But the problem persists.

    I found some information logs in the event viewer:

    Remoteprozeduraufruf (EcDoConnectEx) an Server (SBS) ist mit Fehlercode (721) nach einer Wartezeit von (16) ms fehlgeschlagen; eeInfo (none).

    Does that say something to you. Looks like it would realy be a problem with the RPC calls..

    Greetings, Marcel

  • Another Question..
    The RPC connection works sometimes.. So that means that there is no FQ. Maybe This RPC Ping utility won't show important informations, but i'll try.

    Greetings, Marcel

  • Hello,
    This situation can be occurred when Exchange Server is overloaded and the Client access server RPC cannot checks the required services then the Exchange Server need to resolve this issue or you can resolve this issue by activating the cache mode this will minimize the exchange server subsequently.