XCON: Adjustment of Connection Retry Values on Override Tab

ID: Q157630

The information in this article applies to:
  • Microsoft Exchange Server, versions 4.0, 5.0, 5.5

SUMMARY

In network environments where connectivity is inconsistent and/or unreliable, the MSExchangeMTA may routinely log X.400 Service errors in the Windows NT Event Viewer Application log if mail is queued up to an X.400 Connector that cannot successfully connect to the computer specified on the X.400 Connector's Stack tab in the Microsoft Exchange Administrator program.

If the Microsoft Exchange Message Transfer Agent (MTA) is unable to make the connection to the remote computer due to network problems, it is designed to continue to retry every 600 seconds, by default, until a specified number of retries has been reached (144, by default). Eventually, the MTA will generate a Non-Delivery Report (NDR) to the originator of the message and cease attempts to deliver to the remote computer.

Based on the Microsoft Exchange administrator's needs, these defaults may be set differently on each X.400 Connector, depending on the reliability of the network link between the local and remote computers.


MORE INFORMATION

The following series of Event Viewer errors may indicate that networking problems are contributing to the MTA's inability to deliver mail across the X.400 Connector:

Warning Event ID 1294 Source: MSExchangeMTA Category: X.400 Service:

An association with entity
/O=orgname/OU=site/CN=Configuration/CN=Connections/CN=X400ConnectorName ended abnormally.
Warning Event ID 4284 Source: MSExchangeMTA Category: X.400 Service:

An error occurred during connection/disconnection. Error code: 8511.
Warning Event ID 289 Source: MSExchangeMTA Category: X.400 Service:

A connection to
/O=orgname/OU=site/CN=Configuration/CN=Connections/CN=X400ConnectorName could not be opened.
Information Event ID 301 Source: MSExchangeMTA Category: X.400 Service:

An open retry delay timer started on the association to /O=orgname/OU=site/CN=Configuration/CN=Connections/CN=X400ConnectorName on control block <##>. Another attempt to reopen the association will be made in 600 seconds."
Also, the NDR that is generated may appear as follows: 

   >----------
   >From:   System Administrator
   >Sent:   Friday, September 27, 1996 12:53 PM
   >Subject:   Undeliverable: Exchange 4.5
   >
   >Your message did not reach some or all of the intended recipients.
   >
   >      Subject:   Exchange 4.5
   >      Sent:   9/27/96 12:51:32 PM
   >
   >The following recipient(s) could not be reached:
   >
   >      David Honis on 9/27/96 12:53:24 PM
   >            The recipient could not be processed due to congestion in
   >            the message transfer service
   >*  MSEXCH:MSExchangeMTA:SiteName:ServerName
The administrator can change the Connection Retry options (these definitions are taken from the Online Help, F1, on the Override tab) on the Override tab of the affected X.400 Connector:

  1. Max Open Retries controls the maximum number of times that the system attempts to open a connection before it sends a NDR (default is 144). Increasing this value will allow NDRs to be delayed (total time delay in sec = Max Open Retries X Open Interval) when there are known network problems that will be corrected.


  2. Max Transfer Retries controls the number of times that the system tries to transfer a message across an open connection (default is 2). Increasing this value will also delay the amount of time before the MTA gives up on delivery and generates an NDR.


  3. Open Interval (sec) controls the amount of time to wait before attempting to reopen a connection after an error (default is 600).


  4. Transfer Interval (sec) controls the amount of time to wait before resending a message across an open connection after a previous attempt failed (default is 120).


An Example Showing How All Of These Settings May Be Used

  1. Assume MTA1Machine successfully makes connection to MTA2Machine after mail is queued up to the X.400 Connector going to MTA2 on MTA2Machine.


  2. MTA1 unsuccessfully attempts to send the message over the open connection every Transfer Interval seconds until Max Transfer Retries is reached.


  3. MTA1Machine waits Open Interval seconds before re-attempting to open the connection and fails to make the connection.


  4. The MTA1Machine continues to wait Open Interval seconds between attempts to reconnect and finally generates an NDR after Max Open Retries attempts.


As can be seen from the above example, the amount of time before an NDR is generated is dependent on all of these variables. With the default values on the MTA, an NDR will be generated after 24 hours (144 attempts times 600 seconds is 86,400 seconds, which is 24 hours) assuming the connection failed 144 times. If the connections are intermittently dropping, this calculation becomes less predictable.

Additional query words: Override

Keywords : XCON exc4 exc5 exc55
Version : winnt:4.0,5.0,5.5
Platform : winnt
Issue type : kbhowto


Last Reviewed: January 11, 2000
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