Server Configuration

Server Configuration

This section explains how to configure the server level anti-spam settings which consist of: configuring and enabling the DNS black lists, and configuring the logging options.

Configuring DNS Black Lists

DNS black lists must be configured and enabled for the server before they can be used by hosts. This is done on the DNS Black Lists tab shown below.

All black lists that are configured for the server are displayed here. From this tab, you can add, edit, delete, enable and disable server black lists. Server black list information displayed on this tab is stored in the spamblkm.txt file, located in the IMail top directory.

There are many black lists to choose from. To find other black lists, do an Internet search on the term black list.

Getting to the DNS Black Lists tab

In the left panel, expand the localhost folder, and select the Antispam folder.
In the right panel, click the DNS Black Lists tab.

Configuring a DNS Black List for the Server

To configure a black list for the server, complete the following steps:

On the DNS Black Lists tab, click Add to open the Add DNS BlackList dialog box.
Enter the requested information in the Add DNS BlackList dialog box and click OK. See below for explanations of each option.
To save the black list properties, click Apply at the top of the right panel.

Note: Only black lists that are configured and enabled on this tab are available for use by a host. Once a black list is enabled for the server, it must be enabled for the host on the Connection Filtering tab.

Options

Name. Enter a display name for the black list. This can be any name that you want, and does not have to correspond to the actual name of the black list. This name will be used in log files and X-Headers to identify the black list.

Server. Enter the domain name or IP address of the DNS server to contact for black list queries. By default, this field contains an asterisk (*) for all new black lists. An asterisk employs the use of the IMail DNS server, configured during installation, to contact the black list. The default DNS server relays the DNS query to the DNS server for the black list. When an asterisk is entered, you do not need to enter the IP address or domain for the black list.

Query Domain. The domain to contact for black list queries. This name usually matches the server domain name. However, sometimes a black list contains multiple domains on the same server to differentiate why an IP is black listed. When this is the case, the server name and the query domain will be different. Contact the black list to determine the Query Domain.

Type. The type of lookup done by the black list. Select from the following types:

ADDR (address). Checks the "FROM" address to determine whether the message is spam.
DNS. Checks the IP address of the connecting SMTP agent against spam databases to determine whether the message is spam. If the IP address is listed in one of the black lists, the message is identified as spam.
HELO. Checks the domain supplied in the HELO or EHLO command to determine whether the message is spam. The host name given in the HELO/EHLO command must match the IP address.
RHS (right-hand side). Checks the information following the @ symbol, supplied in the "MAIL FROM" command, to determine whether the message is spam.

Enabled. This setting determines whether hosts can use the black list. When enabled, the black list appears on the Add DNS BlackList dialog box for a host. If this option is cleared, the black list is not displayed on the Add DNS BlackList dialog box for the host, but is still displayed at the server level.

TCP/IP First. Some black lists, especially ones that supply TXT records, have packets too large to transmit via the UDP protocol. These black lists sometimes disable UDP and require the use of TCP to query the black list. This option allows administrators to identify a list as one of these types.

Enabling/Disabling DNS Black lists

DNS black lists can be enabled and disabled directly from the DNS Black Lists tab, by doing the following:

Select the black list from the list box, and click either Enable or Disable.

A DNS black list must be enabled at the server level in order for it to be available for use by hosts. If a DNS black list is disabled, it is not available for hosts. If a DNS black list is in use by a host, but is then disabled at the server level, the black list is immediately disabled for the host and removed from the Connection Filtering tab.

Enabling Logging

Anti-spam logging is separate from other IMail Server logging and is configured on the anti-spam Logging tab. For more information on how to configure logging options, as well as how to read the log files, see "Logging".

Note: Only black lists that are configured and enabled on this tab are available for use by a host. Once a black list is enabled for the server, it must be enabled for the host on the Connection Filtering tab.

Ipswitch, Inc.
http://www.ipswitch.com


©Ipswitch 2004