Use the SMTP Site property sheet to designate the port that Microsoft SMTP Service uses to receive incoming messages and manage the flow of transmissions. You can select the TCP port used to receive messages, determine how many simultaneous open connections the site can have, and set a time-out option to indicate when to close an inactive connection.
| Option | Description |
| TCP Port | Designates the TCP port used for incoming transmissions. The default is port 25. The incoming port setting can be the same as that for outgoing transmissions, or it can be different. |
| Limited to | Specifies the number of concurrent connections for incoming message delivery. The default is 1000 connections. The minimum is 1. The default for incoming connections is higher than that for outgoing connections because the capacity of the servers in which messages are delivered is unknown. |
| Connection time-out (seconds) | Specifies the time allowed before an inactive connection is closed. The default is 600 seconds. |
For an overview of how Microsoft SMTP Service processes incoming messages, see Introduction to Microsoft SMTP Service.