Topic Last Modified: 2007-01-22
A connection is initiated whenever a message is sent to or received from a remote server.
 Important: |
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| Setting connection limits and imposing connection timeouts can make it more difficult for someone to initiate a denial of service attack (DoS) or other malicious attack against your virtual server. |
| Note: |
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| When configuring incoming connections, you designate the TCP port that the SMTP service uses to receive incoming messages when you identify the Simple Mail Transfer Protocol (SMTP) virtual server. For instructions about how to identify SMTP virtual servers, see Configure the SMTP Virtual Server. |
Procedure
To configure
incoming connections
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In Microsoft Management Console, select the SMTP virtual server, and then click Properties on the Action menu.
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On the General tab, select the Limit number of connections to check box and set the following options
|
Option |
Description |
|
Limit number of connections to |
When the check box is selected, this option specifies the number of concurrent connections for incoming message delivery. The minimum is one connection. When the check box is not selected, no limit is imposed. The default value is no limit. |
|
Connection time-out (minutes) |
This option specifies the time allowed before an inactive connection is closed. The default is 10 minutes. |
To configure
outbound connections
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In Microsoft Management Console, select the SMTP virtual server, and then click Properties on the Action menu.
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On the Delivery tab, click Outbound connections to open the Outbound Connections dialog box.
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Under Outbound Connections, select the check box and set the following options.
|
Option |
Description |
|
Limit number of connections to |
When the check box is selected, this option specifies the total number of simultaneous outbound connections to all remote domains that can exist at the same time. The default is 1000 connections. The minimum is 1. The default value is no limit. This setting can be used to improve system performance together with Limit number of messages per connection to on the Messages tab. For more information and instructions about how to limit the number of messages per connection, see Limiting Number of Messages per Connection. |
|
Time-out (minutes) |
This option specifies the time allowed before an inactive connection is closed. The default is 10 minutes. |
|
Limit number of connections per domain to |
When the check box is selected, this option limits the number of connections to any single remote domain. The default is 100 connections. This number should be less than or equal to the value for the Limit number of connections to option. |
|
TCP port |
This option designates the TCP port that is used for outgoing transmissions. The default is port 25. The outgoing port setting can be the same as that for incoming transmissions, or it can be different. |
For an overview of the processes involved in sending messages, see SMTP Server Concepts.