Applies to: Exchange Server 2007 SP1, Exchange Server 2007Topic Last Modified: 2007-06-27

Use the Limits tab on the Hub Transport properties to specify the number of times that the server will retry message delivery, to set notification for undelivered messages, and to specify connection restrictions.

Retries

• Outbound connection failure retry interval (minutes)   Use this field to specify the retry interval for subsequent connection attempts to a remote server where earlier connection attempts as specified by the transient failure retry attempts and the transient failure retry interval have failed. The default value is 10 minutes. The valid input range is 1 minute to 28800 minutes (20 days). We recommend that you do not modify the default value unless Microsoft Support Services have advised you to do this.
  
• Transient failure retry interval (seconds)   Use this field to specify the interval between each connection attempt that is specified by the transient failure retry attempts. The default value is 300 seconds. The valid input range is 1 second to 43200 seconds (12 hours).
  
• Transient failure retry attempts   Use this field to specify the maximum number of times that a server immediately retries when it encounters a connection failure with a remote server. The default value is 6. The valid input range is 0 to 15. When this parameter is set to 0, the server doesn't immediately try to reconnect.
  

Message expiration

Maximum time since submission (days)   Select this option to specify the expiration time-out for a particular message. If a message remains in the queue for longer than this period of time, the message is returned to the sender as a hard failure. The default value is 2 days. The valid input range is 1 day to 90 days.

Notifications

Notify sender when message is delayed more than (hours)   Use this field to specify how long the server waits before it generates a delivery status notification (DSN) that notifies the sender of a delivery delay. The default value is 4 hours. The valid input range is 1 hour to 720 hours (30 days).

Connection restrictions

• Maximum concurrent outbound connections   Select this option to specify the maximum number of outgoing connections that can be open at a time. If the connection limit is reached, the server does not initiate new connections until the number of current connections decreases. The default value is 1000. The valid input range is 1 to 2147483647. To disable this restriction, clear the check box next to Maximum concurrent outbound connections.
  
• Maximum concurrent outbound connections per domain   Select this option to specify the maximum number of concurrent connections to any single domain. The default value is 20. The valid input range is 1 to 2147483647. To disable this restriction, clear the check box next to Maximum concurrent outbound connections per domain.