Symantec Mail Security, Administration Manual

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239 Glossary
Control Center A Web-based configuration and administration center for Symantec Mail Security for
SMTP. Each site has one Control Center. The Control Center also houses Spam Quarantine
and supporting software. You can configure and monitor all of your Scanners from the
Control Center.
defer An action that an MTA receiving an email message can take, which consists of using a 4xx
SMTP response code to tell the sending MTA to try again later.
dialog box A secondary window containing command buttons and options available to users for
carrying out a particular command or task.
dictionary A list of words and phrases against which email messages can be checked for non-
compliant content. Symantec Mail Security for SMTP allows you to create Content
Compliance filters that screen email against a specific dictionary. You can use the provided
dictionaries, add terms to the provided dictionaries, or add additional dictionaries.
directory harvest attack A high volume email campaign addressed to dictionary-generated recipient addresses on a
specific domain. Directory harvest attacks (DHAs) not only consume resources on the
targeted email server, they also provide the spammers with a valuable list of valid email
addresses (targets for future spam campaigns). Symantec Mail Security for SMTP allows
you to identify and defuse directory harvest attacks.
DMZ (de-militarized
zone) A network added between a protected network and an external network to provide an
additional layer of security. Sometimes called a perimeter network.
DNS (Domain Name
Server) proxy An intermediary between a workstation user and the Internet that allows the enterprise to
ensure security and administrative control.
DNS (Domain Name
System) A hierarchical system of host naming that groups TCP/IP hosts into categories. For
example, in the Internet naming scheme, names with .com extensions identify hosts in
commercial businesses.
DNS server A repository of addressing information for specific Internet hosts. Name servers use the
Domain Name System (DNS) to map IP addresses to Internet hosts.
domain 1. A group of computers or devices that share a common directory database and are
administered as a unit. On the Internet, domains organize network addresses into
hierarchical subsets. For example, the .com domain identifies host systems that are used
for commercial business. 2. A group of computers sharing the network portion of their
host names, for example, raptor.com or miscrosoft.com. Domains are registered within the
Internet community. Registered domain entities end with an extension such as .com, .edu,
or .gov or a country code such as .jp (Japan).
downstream At a later point in the flow of email. A downstream email server is an email server that
receives messages at a later point in time than other servers. In a multiple-server system,
inbound mail travels a path from upstream mail servers to downstream mail servers.
Downstream can also refer to other types of networking paths or technologies.