Set SMTP IP Address and Domain Name Restrictions

You can grant or deny SMTP virtual server access to specific users or groups, which you specify by IP address or domain name. By default, the SMTP virtual server is accessible to all IP addresses. You can set restrictions by specifying a single IP address, a group of addresses using a subnet mask, or a Windows 2000 domain name.

Tip   If you choose to grant or deny access based on domain name, you will get a warning window informing you that a Domain Name System (DNS) reverse lookup on each connection will be necessary. Reverse DNS lookups are expensive and could tax your system, so be sure your system can handle the additional processing if you select this option.

To set IP address and domain name restrictions:

1. Start System Manager
   On the Start menu, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. Navigate to the SMTP virtual server.
   1. Servers
   2. Server
   3. Protocols
   4. SMTP
   5. SMTP virtual servers
   6. SMTP virtual server
3. Right-click the SMTP virtual server, and then click Properties.
4. On the Access tab, under Connection control, click Connection.
5. In Connection, select either Only the list below or All except the list below, and then click Add.
6. In Computer, select either Single computer, Group of computers, or Domain, and then fill in the necessary information to define your selection.

7. Tip   For the Single computer option, if you don't know the IP address of the computer, click DNS Lookup, and then type in the name of the computer. Exchange will fill in the IP address for you.

8. Click OK and your entry will be added to the list of computers granted or denied access to the SMTP virtual server.

Note   To delete from the list of computers, select an entry, and then click Remove.