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ACL—Stands for Access Control Lists. ACL is an extension to the Internet Message Access Protocol (IMAP4) that makes it possible for you to create an access list for each of your IMAP message folders, thus granting access to your folders to other users whom also have accounts on your mail server. Further, you can set permissions governing the extent to which each user has control over those folders. For example, you can designate whether or not a user is allowed to delete messages, flag them as read or unread, copy messages to folders, create new subfolders, and so on. Only email clients that support ACL can be used to share this access and set permissions. However, if your email client doesn't support ACL you can still set these permissions from the MDaemon interface.

ACL is fully discussed in RFC 2086, which can be viewed at:

ASCII—Pronounced as-key, ASCII is an acronym for "American Standard Code for Information Interchange". It is the worldwide standard code for representing all upper and lower-case Latin letters, numbers, and punctuation as a 7 digit binary number, with each character assigned a number from 0 to 127 (i.e. 0000000 to 1111111). For example, the ASCII code for uppercase M is 77. The majority of computers use ASCII codes to represent text, which makes it possible for them to transfer data to other computers. Most text editors and word processors are capable of storing files in ASCII format (sometimes called ASCII files). However, most data files—particularly those containing numeric data—are not stored in ASCII format.

Several larger character sets have 128 additional characters because they use 8 bits instead of 7. These extra characters are used to represent symbols and non-English characters. The DOS operating system uses a superset of ASCII called extended ASCII or high ASCII. A standard that is closer to universal, however, is ISO Latin 1, which is used by many operating systems and Web browsers.

ATRN—See ETRN and ODMR below.

Attachment—A file attached to an email message. Most email systems only support sending text files as email, therefore if the attachment is a binary file or formatted text file (e.g. a word processor document), it must first be encoded as text before it is sent and then decoded once it is received. There are a number of encoding schemes—two of the most prevalent being Multipurpose Internet Mail Extensions (MIME) and Unix-to-Unix encode (Uuencode). For incoming messages, Alt-N's MDaemon server can be configured to either leave the decoding process to the recipient's email client or automatically decode attachments and store them in a specific location before delivering the message to the local user.

Backbone—A line or series of connections that form the major pathway within a network. This term is relative since the non-backbone lines in a large network might be larger than the backbone in a smaller network.

Bandwidth—The amount of data that can be transmitted in a fixed amount of time through a network or modem connection, usually measured in bits-per-second (bps). A full page of English text is about 16,000 bits, which a fast modem could transfer in about 1 to 2 seconds. Full-motion full-screen video would require roughly 10,000,000 bits-per-second, depending on compression.

A good illustration of bandwidth is a highway. The highway represents the connection while the cars traveling on it represent the computer data. The wider the highway (the greater the bandwidth) the more cars that will be able to travel on it.

Baud—Baud rate is a measure of how frequently carrier signals change value on a phone line. It is a reference to the speed at which a modem transmits data. Usually, slower modems are described in terms of Baud rate while higher speed modems are described in bits per second. "Baud rate" and "bits per second" are not necessarily synonymous terms since each signal can encode more than one bit in high-speed connections.

Bit—A single Binary digit. It is the smallest unit of computer data; a single digit number in base-2 (i.e. 0 or 1). It is usually abbreviated with a lower case "b" as in "bps" (bits per second). A full page of text is approximately 16,000 bits.

Bitmap—Most pictures you see on your computer, including all the ones found on the Internet, are bitmaps. A bitmap is a really just a map of dots (or bits) that looks like a picture as long as you're not to close to the screen, or have the bitmap magnified too much, to see the shape they make. Common Bitmap file types include BMP, JPEG, GIF, PICT, PCX, and TIFF. Because bitmap images are made up of a bunch of dots, if you zoom in on a bitmap it looks blocky rather than smooth. Vector graphics (usually created in CorelDraw, PostScript, or CAD formats) scale up much better because they are geometric shapes generated mathematically rather than simply being made of seemingly "random" dots.

Bps—"Bits Per Second" is a measurement of how fast computer data can be moved from one place to another. For example, a 33.6 kbps modem can transfer 33,600 bits per second. Kilobits (1000 bits) per second and megabits (1.000,000 bits) per second are abbreviated "Kbps" and "Mbps" respectively.

Browser—Short for "Web browser", it is an application used to display web pages. It interprets HTML code, text, hypertext links, images, JavaScript, and so on. The most widely distributed browsers are Internet Explorer and Netscape Communicator.

Byte—A set of bits (usually eight) that represent a single character. There are 8 bits in a byte, sometimes more, depending on how the measurement is being made. "Byte" is abbreviated with an uppercase "B".

Cache—Pronounced like "cash". There are various types of caches, but all are used to store recently used information so that it can be accessed quickly later. For example, a web browser uses a cache to store the pages, images, URLs, and other elements of web sites that you have recently visited. When you return to a "cached" page the browser will not have to download these elements again. Because accessing the cache on your hard disk is much faster than accessing the Internet, this significantly speeds up browsing.

MDaemon's IP Cache stores the IP addresses of domains to which you have recently delivered messages. This prevents MDaemon from having to lookup these addresses again when delivering additional messages to the same domains. This can greatly speed up the delivery process.

CGI—Common Gateway Interface is a set of rules that describe how a Web Server communicates with another piece of software on the same machine, and how the other piece of software (the "CGI program") talks to the web server. Any piece of software can be a CGI program if it handles input and output according to the CGI standard. However, a CGI program is usually a small program that takes data from a web server and does something with it, like putting the content of a form into an email message, or doing something else with that data. CGI programs are often stored in a web site's "cgi-bin" directory and therefore appear in a URL that accesses them, but not always.

cgi-bin—The most common name of the directory on a web server in which CGI programs are stored. The "bin" part of "cgi-bin" is short for "binary" because most programs used to be referred to as "binaries". In reality, most cgi-bin programs are text files; scripts executed by programs located elsewhere.

CIDR—"Classless Inter-Domain Routing" is a new IP addressing system that replaces the older system, which was based on classes A, B, and C. CIDR IP addresses look like normal IP addresses followed by a slash and number, called the IP prefix. For example:

The IP prefix defines how many addresses are covered by the CIDR address, with lower numbers covering more addresses. In the above example, the IP prefix of "/12" can be used to address 4,096 former Class C addresses.

CIDR addresses reduce the size of routing tables and make more IP addresses available within organizations.

CIDR is addressed in RFCs 1517-1519, which can be viewed at:

Client—A software program that is used to contact and obtain data from or send data to a server software program. The server is usually located on another computer, either on your local network or at some other location. Each client program is designed to work with one or more specific kinds of server programs, and each server requires a specific kind of client. A web browser is a specific kind of client that communicates with web servers.

Common Gateway Interface—See CGI above.

Cookie—In computer terminology, a cookie is data sent by a web server to your web browser, which is saved and later used for various purposes when you return to the same site or go to another location on the site. When a web server receives a request from a web browser that includes a cookie, it is able to use the information the cookie contains for whatever purpose it was designed, such as customizing what is sent back to the user, or for keeping a log of the user's requests. Typically, cookies are used for storing passwords, usernames, preferences, shopping cart information, and similar things related to the site to which they correspond so that the site can appear to "remember" who you are and what you've done there.

Depending on your browser's settings, you may accept or not accept the cookies, and save them for various amounts of time. Usually cookies are set to expire after a predetermined amount of time and are saved in memory until the web browser software is closed down, at which time they may be saved to disk.

Cookies cannot read your hard drive. They can, however, be used to gather information about you related to your usage of their particular web sites, which would be impossible without them.

Dial-up Networking—A component in Windows that enables you to connect your computer to a network via a modem. Unless your computer is connected to a Local Area Network (LAN) with access to the Internet, you will need to configure Dial-Up Networking (DUN) to dial a Point of Presence (POP) and log on to your Internet Service Provider (ISP) before you will have Internet access. Your ISP may need to provide certain information, such as the gateway address and your computer's IP address.

DUN is accessed through the My Computer icon. A different dialup profile can be configured for each online service that you use. Once configured, you can copy a profile shortcut to your desktop so that all you need to do to make a connection is double-click the connection icon.

Default—This term is used to refer to the preset value for options in computer programs. Default settings are those settings which are used when no specific setting has been designated by the user. For example, the default font setting in Netscape Communicator is "Times". This setting will remain "Times" unless you change it to something else. Default settings are usually the value that most people will choose.

Frequently the term default is also used as a verb. If a custom setting won't work or the program lacks some needed bit of data for completing a task, it will usually "default" to a specific setting or action.

DHCP—An acronym for "Dynamic Host Control Protocol". Network servers use this protocol to dynamically assign IP addresses to networked computers. A DHCP server waits for a computer to connect to it and then assigns it an IP address from a stored list.

DHCP is addressed in RFC-2131, which can be viewed at:

Domain Gateway—See Gateway below.

Domain Name—This is the unique name that identifies an Internet web site. For example, "" is the domain name of Alt-N Technologies. Each domain name contains two or more parts separated by dots; the leftmost part is the most specific while the rightmost part is the most general. Each domain name also points to the IP address of a single server, but a single server may have more than one domain name. For example, "", "", and "" could all point to the same server as "", but "" could not point to two different servers. There are, however, methods for designating alternate servers to which clients will be directed if the main server goes down or is otherwise unavailable.

It is also common for a domain name to be registered but not be connected to an actual machine. The usual reason for this is the domain name's owner hasn't created a web site yet, or so that they can have email addresses at a certain domain without having to maintain a web site. In the latter case, there must be a real Internet machine to handle the mail of the listed domain name.

Finally, it is common to see the term "domain name" shortened and referred to as simply "domain". The word "domain" has other meanings and can refer to other things, such as a Windows NT domain or a class of values, so you should be aware of the distinction in order to avoid confusion.

Domain Names are addressed in RFCs 1034-1035, which can be viewed at:

DomainPOP—Developed by Alt-N Technologies to be a part of the MDaemon server, DomainPOP makes it possible to provide email services for an entire LAN or workgroup from a single ISP POP mailbox. In the past, unless a company's email server had on constant "live" connection to the Internet, the only way to provide Internet email services to a workgroup was for each person to have their own mailbox on the company's ISP from which they could collect their mail. With DomainPOP only a single mailbox is required. The ISP pools all mail for the company's domain name into the mailbox from which it is periodically collected by DomainPOP. Then, DomainPOP parses the messages to determine the intended recipients of each and distributes them to the appropriate local user mailboxes. Thus email is provided for an entire network from a single dialup ISP account.

Download—The process by which your computer retrieves or obtains data from another computer. For example, information is obtained from the Internet by downloading it from other computers. The reverse of this is uploading. If you wish to send information to another computer then you will upload it to them.

Driver—A small program that communicates with a certain hardware device. Drivers contain information needed by the computer and other programs to control and recognize the device. Windows-based computers often have drivers packaged as a dynamic link library (DLL) file. Most hardware devices used with Macs do not need drivers, but when a driver is necessary it will usually come in the form of a System Extension.

DUN—See Dial-up Networking above.

Email—Stands for "Electronic mail". This term also appears in the forms: "E-mail", "e-mail", and "email"; all have the same meaning. Email is the transmission of text messages over communications networks. Most computer networks have some form of email system. Some email systems are confined to a single computer network, but others have gateways to other networks (which enables them to communicate with multiple locations), or to the Internet (which enables them to send email anywhere in the world).

Most email systems include some form of email client (also referred to as a mail client or just client) which contains a text editor and other tools for composing messages, and one or more servers which receive the email from the clients and route it to its appropriate destination. Typically, a message is composed using the client, passed to a server for delivery to the email address (or addresses) specified in the message, and then routed by the server to another server that is responsible for storing messages destined for that address. If the message's destination is a local address for which the original server is responsible then it may be stored on the original server rather than routed to another. Last, the recipient of the message will connect to their server and retrieve the message by using their email client. This entire process of transferring an email message from your client to its destination server usually only takes a few seconds or minutes.

Besides containing simple text, email messages may also include file attachments. These attachments can be any type of file that you desire: pictures, text files, program files, other email messages, and so on. However, since most email systems only support sending text files, attachments must first be encoded (converted to a text format) before they can be sent, and then decoded when they arrive at their final destination. This process is usually done automatically by the sending and receiving mail clients.

All Internet Service Providers (ISPs) offer email. Most also support gateways so that you can exchange email with users of other email systems. Although there are many different protocols used for processing email by many different email systems, several common standards make it possible for users on virtually all systems to exchange messages.

Email Address—A name or string of characters that identifies a specific electronic mailbox on a network to which email can be sent. Email addresses are the locations to and from which email messages are sent. Email servers need email addresses so that they can route messages to their proper destinations. Different types of networks have different formats for email addresses, but on the Internet all email addresses have the form: "".

For example,

Email Client—Also called a mail client (or just client), an email client is a software application that enables you to send, receive, and organize email. It is called a client because email systems are based on client-server architecture; a client is used to compose the email and then send it to a server, which then routes it to the recipient's server from which it will be retrieved by the recipient's client. Usually, email clients are separate software applications installed on the user's machine, but products such as Alt-N Technologies' WorldClient Server contain a built in client that is "served" to the user's web browser. Thus, their browser is used as the client rather than needing to install one on their machine. This greatly enhances the portability and convenience of email.

Encryption—A security measure, encryption is the coding or scrambling of information in a file so that it will only be intelligible when it has been decoded or decrypted. Encryption is frequently used in email so that if a third party intercepted the email they would not be able to read it. The message is encrypted when it is sent and then decrypted at its final destination.

Ethernet—The most common type of connection used in a Local Area Network (LAN). Two of the most widely used forms of Ethernet are 10BaseT and 100BaseT. A 10BaseT Ethernet can transfer data at speeds up to 10 mbps (megabits per second) through a cable or wireless connection. A 100BaseT Ethernet transfers data at speeds up to 100 mbps. A Gigabit Ethernet can transfer data at rates up to 1000 mbps and is employed by some Apple computers.

ETRN—An acronym meaning Extended TURN. It is an extension to SMTP that enables an SMTP server to send a request to another SMTP server to send, or "dequeue", mail that is being held for it. Because SMTP by itself cannot request mail (email is usually requested via the POP or IMAP protocols), this makes it possible for the SMTP server making the ETRN request to cause the remote server to start an SMTP session and begin sending the stored email to the host specified in the request.

The TURN command used for this purpose posed a security risk because it caused the SMTP session to reverse direction and begin sending the stored mail immediately without any verification or authentication that the requesting server was actually who it claimed to be. ETRN starts a new SMTP session rather than reversing direction. Thus if the server making the request is a "spoofed" host, the sending server will still attempt to deliver the mail to the real host instead. There is now a proposed standard that introduces Authenticated TURN (ATRN), which, like TURN, reverses the direction of the SMTP session but requires authentication before doing so. This new standard is On-Demand Mail Relay (ODMR). Alt-N Technologies' MDaemon server supports both ETRN and ODMR's ATRN.

ETRN is addressed in RFC 1985, which can be viewed at:

ODMR is addressed in RFC 2645, which can be viewed at:

FAQ—Pronounced together as "fack" or as separate letters "F-A-Q", FAQ stands for "Frequently Asked Questions". FAQs are documents that provide answers to the most commonly asked questions on a given subject. They usually appear in some form of list format with each question listed first followed by its answer. In larger FAQs, oftentimes all of the questions will be listed at the beginning of the document with references (or hyperlinks, in online FAQs) to the location of the question and answer in the document. FAQs are frequently used as a starting point for technical support and instructions—a great deal of time and effort can be saved if you have access to a FAQ that answers your question instead of being forced to contact technical support.

File Transfer Protocol—See FTP below.

Firewall—In computer terminology, a firewall exists when you undertake security measures, through either software or hardware means, to separate a computer network into two or more parts, or otherwise limit access to it to certain users. For example, you might want to let everyone view the home page of a web site hosted on your network but allow only your employees to get to an "employee only" area. Regardless of the method that you use to accomplish this—requiring a password, allowing connections from only certain IP addresses, or the like—the employee area is said to be behind a firewall.

FTP—Acronym for "File Transfer Protocol." It is a common and efficient method of transferring files via the Internet from one computer to another. There are specific client/server applications designed for this purpose called "FTP servers" and "FTP clients"—FTP Voyager and CuteFTP are two of the most common clients. Usually FTP clients can perform quite a few other functions besides simply transferring files and are thus highly useful products. Some web browsers also contain support for File Transfer Protocol, though sometimes for downloading only. Additionally, most FTP servers are "anonymous FTP", which means that anyone can log in to them in order to download files—usually by specifying "anonymous" as the user name and then your email address as the password. Oftentimes you can download files from anonymous FTP sites without having to log in at all—they can be retrieved by simply clicking on a link. For browsers that support FTP, usually all that needs to be done is to connect to the FTP site using "ftp://…" in its URL rather than "http://…"

FTP is addressed in RFC-959, which can be viewed at:

Gateway—Computer hardware or software that translates data between two applications or networks with protocols that are dissimilar. "Gateway" is also used to describe any means by which access is provided from one system to another. For example, your ISP is a gateway to the Internet.

Alt-N Technologies' MDaemon email server can function as an email gateway for other domains through the use of its Domain Gateways feature. It acts as an intermediary, or Gateway, by collecting the domain's email and then holding it until the domain collects it. This is useful both for domains that do not maintain a continuous connection to the Internet and for domains that require a backup server in case theirs goes down.

GIF—"Graphics Interchange Format" is a popular format for image files and is the most common format of images found on the Internet. GIF uses indexed colors or a palette of a certain number of colors, which greatly reduces file size—especially when the image contains large areas of the same color. The reduced size enables them to be quickly transferred between systems and accounts for their popularity on the Internet. The GIF compression formula was originally developed by CompuServe and thus you will often see GIF referred to as CompuServe GIF.

Graphical User Interface—See GUI below.

GUI—Pronounced "gooey", this acronym stands for "Graphical User Interface". A GUI makes it possible to interact with your computer or application by using a pointing device to click graphical elements on the screen rather than typing in text at a command line. The Microsoft Windows and Apple Mac operating systems are both GUI-based, but—although first introduced by Apple—the idea of a graphical user interface actually originated from Xerox.

Host—Any computer on a network that acts as a server for other computers on the same network. The host machine may be running a web server, email server, or other services, and it is common for it to provide several services at once. Host is also often used in the verb form "to host". For example, a machine running an email server would be "hosting" the email.

On peer-to-peer networks it is common for machines to be both hosts and clients at the same time. For example, your machine may host your network's printer but also be used by you as a client to collect email and download files from another host.

HTML—An acronym for "Hypertext Markup Language. It is the coding language used to create Hypertext documents used on the World Wide Web. Simply put, an HTML document is a plain text document that contains formatting codes and tags that the user's web browser interprets and presents as a web page complete with formatted text and colors. For example, a browser receiving an HTML document containing the text "<B>Text</B>" would present the word "Text" in Bold. Because plain text files are very small, this makes it possible for them to be quickly transferred over the Internet.

HTTP—Hypertext Transfer Protocol (HTTP) is the protocol used for transferring hypertext files between computers over the Internet. HTTP requires a client program on one end (usually a web browser) and an HTTP server on the other end.

HTTP is addressed in RFC-2616, which can be viewed at:

Hypertext—Any text that contains a hyperlink or jump to another document or place within the same document is called hypertext. Sometimes the text is also called a hypertext link or simply link. Hypertext can be either a word or phrase and has the link embedded in it so that clicking it will move you to the "book marked" location or cause the linked document to be displayed. Usually hypertext links are apparent because the text is underlined and a different color, but that is not required. Sometimes hypertext will look no different than normal text, but will almost always be indicated by some sort of graphical change to your pointer when the mouse pointer is paused over it.

Hypertext Markup Language—See HTML above.

IMAP—Developed by Stanford University, Internet Message Access Protocol (IMAP) is a protocol used for managing and retrieving email messages. The latest version is IMAP4 and is similar to POP3 but with a number of additional features. IMAP4 is best known as a protocol used for managing email messages on the server rather than on the user's local machine—messages can be searched for keywords, organized in folders, specifically selected for downloading, and other features, all while they are still on the server. Thus IMAP places less demand on the user's machine and centralizes email so that it can be accessed from multiple locations.

IMAP is addressed in RFC-2060, which can be viewed at:

IMAP4 ACL extension—See ACL above.

Internet—The Internet was created in 1969 by the United States military, originally to be a communications network that couldn't be destroyed during a nuclear war. It now consists of millions of computers and networks all over the world. By design, the Internet is decentralized—it is not controlled by any company, organization, or country. Each host (or machine) on the Internet is independent of the others and can provide whatever information or services its operators wishes to make available. Nevertheless, most information transferred over the Internet at some point passes through "backbones", which are extremely high-bandwidth high-speed connections controlled by the largest Internet Service Providers and organizations. Most people access the Internet through an online service such as AOL or through an Internet Service Provider (ISP) that maintains or is connected to one of these backbones.

Many people believe that the World Wide Web (WWW) and the Internet are the same thing, but this is not the case. The WWW is only one part of the Internet not the Internet itself. It is the most visible and popular part, largely driven by commerce, but still only a part.

Intranet—Simply put, an intranet is a small or private Internet used strictly within a company or organization's network. Although intranets vary widely from organization to organization, they may contain any of the features available on the Internet. They may have their own email systems, file directories, web pages to be browsed, articles to be read, and so on. The primary difference between an intranet and the Internet is that an intranet is relatively small and confined to an organization or group.

IP—An acronym for "Internet Protocol" (e.g. as in TCP/IP). Internet protocols make it possible for data to be transferred between systems over the Internet. Regardless of each machine's platform or operating system, if the same Internet Protocol is used by each machine then they will be able to transfer data to each other. The term "IP" is also commonly used as a further abbreviation of the term "IP Address". The current standard Internet Protocol is IP version 4 (IPv4).

Internet Protocol is addressed in RFC-791, which can be viewed at:

IP Address—Occasionally called an IP Number, IP Address stands for Internet Protocol Address and is used to identify a particular TCP/IP network and the hosts or machines on that network. It is a 32-bit numeric address containing four numbers between 0 and 255 separated by dots (e.g. ""). Within an isolated network, each computer must have a unique IP address, which can be assigned at random. But, every computer on the Internet must have a registered IP address to avoid duplication. Each Internet IP address can be either static or dynamic. Static addresses do not change and always represent the same location or machine on the Internet. Dynamic IP addresses change and are usually assigned by an ISP to computers that are only on the Internet temporarily—such as when a user with a dial-up account accesses the Internet. However, it is still possible for a dial-up account to have a static IP address assigned to it.

ISPs and large organizations usually attempt to acquire a range or set of IP addresses from the InterNIC Registration Service so that all clients on their network or using their service may have similar addresses. These sets are broken up into three classes: Class A, B, and C. Class A and B sets are used by very large organizations and support 16 million and 65,000 hosts respectively. Class C sets are for smaller networks and support 255 hosts. Class A and B sets are now very difficult to get due to the shortage of available addresses; consequently most companies have to settle for multiple class C sets instead. Because of this IP address shortage, there is a new IP address protocol called Classless Inter-domain Routing (CIDR) that is gradually replacing the older system.

The current Internet Protocol standard, IPv4, is addressed in RFC-791, which can be viewed at:

IP version 6 (IPv6) is addressed in RFC-2460 at:

CIDR is addressed in RFCs 1517-1519 at:

IP Number—See IP Address above.

ISP—An Internet Service Provider (ISP) is a company that provides Internet access and services to the end user. Most ISPs provide multiple Internet services to their customers, such as: WWW access, email, access to newsgroups and news servers, and so on. Typically, users will connect to their ISP via dial-up, or some other form of connection, and then the ISP will connect them to a router, which will in turn route them to the Internet backbone.

Java—Developed by Sun Microsystems, Java is a network-oriented computer programming language with syntax much like C/C++ but is structured around classes instead of functions. In Internet applications it is commonly used for programming applets, which are small programs embedded in web pages. These programs can be automatically downloaded and executed by a user's browser in order to provide a large number of functions that wouldn't ordinarily be possible with just HTML or other scripting languages, and without fear of viruses or harm to your computer. Because Java is both efficient and easy to use, it is becoming popular among many software and hardware developers.

JavaScript—Not to be confused with Java, JavaScript was developed by Netscape as a scripting language designed to extend the capabilities of HTML and create interactive web pages. It is a highly pared down and easy to use programming language, which makes it much easier to use than Java and other languages but also limits it to some degree. It spite of its limitations it is very useful for adding a number if interactive elements to web sites. For example, JavaScript is useful when you want data to be preprocessed before it is submitted to the server, or when you want your pages to respond to user interaction with links or form elements. It can also be used to control plug-ins and applets based on user choices, and to accomplish a large number of other functions. JavaScript is included within the text of HTML documents and is interpreted by web browsers in order to perform the functions.

JPEG—A graphics file format that is very efficient at compressing high-color and photographic images—much more so than the GIF format. While GIF is the best choice for images containing regular shapes and large areas of repeating color patterns, JPEG is much more suited to images with irregular patterns and large numbers of colors. JPEG is the most commonly used format for high-color and photographic images on the Internet. The acronym JPEG stands for "Joint Photographic Experts Group"—the group that developed the format.

Kbps—Commonly used when referring to modem speeds (e.g. 56 Kbps), this acronym stands for "Kilobits Per Second". It is the number of kilobits (1000 bits) of data being moved or processed every second. Note that this is kilobits not kilobytes—a kilobyte would be eight times more data than a kilobit.

Kilobyte—A kilobyte (K or KB) is a thousand bytes of computer data. Technically it is 1024 bytes (2^10 = 1024) but in normal usage it is usually rounded off to 1000 for simplicity.

LAN—A Local Area Network (LAN) is a computer network limited to a single building or area, usually having all nodes (computers or workstations) connected together with some configuration of wires or cables or some other form of media. Most large companies have a LAN, which greatly simplifies the management and sharing of information amongst employees and offices. Most LANs utilize some form of email or chat system, and share devices such as printers in order to avoid having to have a separate device for each station. When the network's nodes are connected together via phone lines, radio waves, or satellite links it is called a Wide Area Network (WAN) instead of LAN.

Latency—The time it takes a data packet to move across a network connection. While a data packet is being sent, there is "latent" time during which the sending computer waits for a confirmation that the packet has been received. In addition to bandwidth, latency is one of the factors that determine the speed of your connection.

LDAP—Lightweight Directory Access Protocol (LDAP) is an online directory service protocol that is a simplification of Directory Access Protocol (DAP). The directory system is in a hierarchical structure consisting of the following levels: The "root" or starting directory, country, organization, organizational unit, and individual within that unit. Each LDAP entry is a collection of attributes with a unique identifier, called a distinguished name (DN). Because it is an open protocol, is efficient, and has the ability to be distributed across many servers, LDAP may eventually make it possible for virtually any application on any platform to access directory information for locating email addresses, organizations, files, and so on worldwide.

LDAP is addressed in RFC-2251, which can be viewed at:

Link—See Hyperlink above.

List server—A server application that is used to distribute email messages to multiple recipients by simply addressing the message to a single address. Simply put, when an email message is addressed to a mailing list maintained by the list server it will be automatically broadcast to the members of the list. Mailing lists typically have a single normal email address (for example, but that address refers to a whole list of recipients rather than to a specific person or mailbox. When someone subscribes to a mailing list, the list server will automatically add the address to the list and distribute future emails directed to the list to that address, or member, and all other members. When someone unsubscribes, the list server simply removes the address so that it will receive no further list messages.

Frequently the term listserv is used generically to refer to any mailing list server. However, Listserv® is a registered trademark of L-Soft international, Inc. and is a specific program developed by Eric Thomas for BITNET in 1986. Besides other list servers, Alt-N Technologies' MDaemon server is equipped with an entire suite of list server, or mailing list, functions and features.

Logon—a unique code or series of characters used to gain access or otherwise identify yourself to a server or machine. In most cases a password must accompany the logon in order to gain access.

There are many terms used synonymously with "logon", such as login, username, user name, user ID, sign-in, and others. Frequently, "logon" is also used as a verb. For example, "I am going to logon to the mail server". In that context, however, the more common usage (and perhaps more proper) is "I am going to log on to the mail server".

Mailbox—An area in memory or on a storage device that is assigned to a specific email address and where email messages are stored. In any email system, each user has a private mailbox in which messages are stored when that user's mail server receives them. It is also common for the term "mailbox" to be used when referring to the leftmost portion of an email address. For example, "Frank" in "" is the mailbox while "" is the domain name.

Mailing List—Also called email groups, a mailing list is a list or group of email addresses identified by a single email address. For example, "". Typically when a list server receives an email message addressed to one of its mailing lists that message will be automatically distributed to all of the list's members (i.e. the addresses included in the list). Alt-N Technologies' MDaemon server is equipped with an extensive suite of mailing list features that enable lists to be public or private (anyone can post or join, or only members can post or join), moderated (each message must be approved by someone before it will go to the list), sent in digest format or as individual messages, and used in a variety of other ways.

Megabyte—Though technically 1,048,576 bytes (or 1024 kilobytes), a megabyte is more commonly rounded off and used to refer to a million bytes. Megabyte is abbreviated: "MB", as in "20 MB".

MIME—Defined in 1992 by the Internet Engineering Task Force (IETF), Multipurpose Internet Mail Extensions (MIME) is the standard encoding method used for attaching non-text files to standard Internet email messages. Because typically only plain text files can be transferred via email, non-text files must first be encoding into a plain text format and then decoded after reaching their destination. Thus, an email program is said to be MIME Compliant if it can both send and receive files using the MIME standard. When a MIME-encoded message attachment is sent, generally both the type of file being sent and the method that should be used to turn it back into its original form are specified as part of the message. There are many predefined MIME content types, such as "image/jpeg" and "text/plain". However, it is also possible to define your own MIME types.

The MIME standard is also used by web servers to identify the files they are sending to web browsers. Because web browsers support various MIME types, this enables the browser to display or output files that are not in HTML format. Further, by updating the browser's lists of MIME-Types and the software used for handling each type, new file formats can be readily supported.

MIME is addressed in RFCs 2045-2049, which can be viewed at:

Mirror—A server (usually an FTP server) that has a copy of the same files that are on another server. Its purpose is generally to provide an alternate location from which the mirrored files can be downloaded should the original server go down or be overloaded. The term "mirror" can also refer to a configuration whereby information is written to more than one hard disk simultaneously. This is used as a redundancy measure so that if one disk fails the computer can continue to operate without losing any vital data.

Modem—An acronym derived from modulator-demodulator. A modem is a device connected to a computer that enables the transfer of data to other computers over telephone lines. The modem converts the computer's digital data to an analog format (modulates) and then transmits it to another modem where the process is reversed (demodulates). Put simply, a modem is an analog-to-digital and digital-to-analog converter. The speed at which the data is transferred is expressed in either baud-rate (e.g. 9600 baud) or kilobits per second (e.g. 28.8 kbps).

MultiPOP—A component of Alt-N Technologies' MDaemon email server that can be configured to collect email, via the POP3 protocol, simultaneously from various email servers on behalf of MDaemon's users. This makes it possible for MDaemon account holders who have email accounts elsewhere on other email servers to have that email collected and pooled with their MDaemon account email. Thus storing all of their email in a single mailbox.

NAT—See Network Address Translation below.

Network—Two or more computers connected together in some fashion. The purpose of a network is to enable the sharing of resources and information between multiple systems. Some common examples are: multiple computers sharing printers, DVD-ROM drives, hard disks, individual files, and so on.

There are many types of networks, but the most broadly defined types are Local Area Networks (LANs) and Wide Area Networks (WANs). In a LAN, the individual computers (or nodes) are geographically close together—usually in the same building. They are also usually connected together directly with wires, although wireless connections are becoming common as well. The nodes in a WAN are usually farther apart (in another building or city) and connected via telephone lines, satellite hook-up, or some other form of connection.

The Internet itself is a network. It is often described as a network of networks.

Network Address Translation—Network address translation (NAT) is a system whereby two sets of Internet Protocol addresses (IP addresses) are used by a single network—one for external traffic and the other for internal traffic. This is mainly used as a firewall measure to help ensure network security. Your computer will appear to have a certain IP address to computers outside your LAN while your actual IP address is altogether different. Hardware or software placed "between" your network and the Internet performs the translations between the two addresses. Using this method, it is common for multiple computers in a LAN to "share" one company IP address. Thus there is no way for someone outside your network to know your actual address and directly connect to your computer without it first being qualified or authenticated during the translation.

Network Interface Card—A network interface card (NIC) is a computer circuit board that enables a computer to be connected to a network. NICs provide a full-time network connection whereas a modem (used by most home computers to dial-in to a network via telephone lines) usually provides only a temporary connection. Most NICs are designed for specific types of networks and protocols, such as Ethernet or token ring and TCP/IP.

Network News Transfer Protocol—See NNTP below.

NIC—See Network Interface Card above.

NNTP—Network News Transfer Protocol (NNTP) is the protocol used to transfer and distribute messages on USENET newsgroups. The most common and popular browsers and email clients now have NNTP clients built-in.

NNTP is addressed in RFC-977, which can be viewed at:

Node—Any single computer connected to a network.

ODMR—On-Demand Mail Relay is a new protocol designed to enable mail servers with only an intermittent connection to a service provider, and which do not have a static IP address, to receive mail similarly to those servers that do have one and use the ETRN command. If the system has a static IP address, the ESMTP ETRN command can be used. However, systems with dynamic IP addresses have no widely deployed solution. ODMR solves this problem. Among other things, ODMR introduces the Authenticated TURN command (ATRN) which causes the flow of an SMTP session to be reversed (like the older TURN command) but with the added security of requiring that the requesting server be authenticated. This makes it possible for an SMTP server with a dynamic IP address to connect to its ISP and have one or more host's email delivered to it via SMTP rather than collect it via POP or IMAP. This helps meet the widespread demand for a low-cost solution for those companies that need to their own mail server but cannot afford a static IP address or dedicated online presence.

ODMR is addressed in RFC 2645, which can be viewed at:

OEM—Original Equipment Manufacturer (OEM) is an often confusing and misunderstood term. An OEM is a company that uses another company's equipment or products in its own product that is packaged and sold under a different brand or company name. For example, HyperMegaGlobalCom, Inc. is an OEM because it purchases computer components from one or more different companies, puts them all together into a single customized product, and then sells it with "HyperMegaGlobalCom" stamped on it. The company that sold HyperMegaGlobalCom the components might also be an OEM if they in turn got their components from someone else as well. "OEM" is an unfortunate misnomer because OEMs are not actually the original manufacturers; they are the "packagers" or "customizers". In spite of this, many people still often use the term "OEM" when referring to the actual hardware manufacturers instead of those who repackage it—and understandably so.

On the fly—The term "on the fly" is commonly used it two different ways. First, it is often used to denote something that can be done "in a hurry" or easily while "in the middle" of performing some other task. For example, a bookkeeping product might support creating accounts "on the fly" while in the middle of entering sales figures—"Simply stop entering figures, click button X, enter a name, and then continue entering more figures." The other way that "on the fly" is used is in referring to something that can be generated dynamically or automatically instead of manually or statically. For example, by using the information stored in a "cookie" a customized web page might be generated "on the fly" when a user returns to a web site. Rather than requiring someone to manually create a page customized to the user's tastes, it would be generated dynamically based upon that person's actions while browsing.

Original Equipment Manufacturer—See OEM above.

Packet—A unit of computer data sent over a network. Any time you receive data from another computer on your LAN or over the Internet it comes to your computer in the form of "packets". The original file or message is divided into these packets, transmitted, and then recombined at the destination. Each packet contains a header containing its source and destination, a block of data content, and an error-checking code. It is also "numbered" so that it can be connected to related packets being sent. The process of sending and receiving packets is known as "packet-switching". Packets are also commonly called "datagrams".

Packet Switching—The process of sending and receiving packets over a network or the Internet. In contrast to circuit switching (such as in an analog telephone), which sends the data in a continuous stream over a single path or circuit, packet switching transmits the data broken up into "packets", which may not necessarily take the same route to get to their destination. Further, because the data is in separate units, multiple users can send different files simultaneously over the same path.

Parameter—A parameter is a characteristic or value. In computing, it is any value passed to a program by a user or another program. Your name and password, a preference setting, font size, and so on are all parameters. In programming, a parameter is a value that is passed to a subroutine or function for processing.

PDF—Portable Document Format (PDF) is a highly compressed multi-platform file format developed by Adobe Systems Incorporated that captures document formatting, text, and images from a variety of applications. This makes it possible for the document to appear the same and print accurately on multiple computers and platforms (unlike many word processors). Viewing a PDF file requires the Adobe Acrobat Reader, a free application distributed by Adobe Systems. There is also a plug-in for viewing PDF files with your web browser. This makes it possible to view PDF files posted on a web site directly instead of having to download them first and then view them with a separate program.

Parse—In linguistics, to parse is to divide language into its grammatical components that can be analyzed. For example, dividing a sentence into verbs, adjectives, nouns, and so on.

In computers, to parse is to divide a computer language statement into parts that can be made useful for the computer. A parser in a compiler is takes each program statement that a developer has written and divides it into parts that can then be used for developing further actions or for creating the instructions that form an executable program.

Alt-N Technologies' MDaemon server and other products often parse email messages to determine their destination or to process them through filters and other tools.

Ping—An acronym for Packet Internet Groper. It is a basic Internet program used to determine whether a specific IP address is reachable and accepting requests. It does this by sending an Internet Control Message Protocol (ICMP) Echo request and waiting for a response. "Ping" is commonly used as a verb when referring to this process. For example, "I am going to ping that server to see if it is online." "Pinging" an IP address is usually as simple as typing "ping" followed by the IP address or domain at the DOS prompt. For example "Ping"

ICMP is addressed in RFC-792 and the Echo protocol is addressed in RFC-862. These can be viewed at:

POP—Stands for Post Office Protocol. POP (also commonly appears as POP3) is the most commonly used email protocol for retrieving email from a mail server. Most email clients use the POP protocol although some also support the newer IMAP protocol as well. POP2 became a standard in the mid 1980s and required SMTP to send messages. It was replaced by the newer version, POP3, which can be used with or without SMTP. POP is sometimes used as a verb when referring to collecting your email from a server. For example, "I'm going to POP my mailbox to get my mail."

POP3 is addressed in RFC-1939, which can be viewed at:

Port—In TCP/IP and UDP networks and the Internet, a port is the endpoint of a logical connection and is identified by a number from 0 to 65536. Ports 0 to 1024 are reserved for use by certain privileged protocols and services. For example, web servers typically are listed on port 80, SMTP servers typically communicate on port 25, and POP servers send and receive mail on 25. Generally, only one program at a time can use, or "bind", to any given port on each machine. When browsing the Internet, oftentimes certain servers will be running on non-default ports, which require you to specify the port in the URL after a colon. For example, ""

Port can also be used to refer to the sockets on a computer used for connecting peripheral devices and hardware to it. For example, serial ports, parallel ports, USB ports, and so on.

Finally, port is often used to describe the process of making a program designed for a specific platform or machine function on another platform. For example, "to port a Windows application to UNIX" or "to create a UNIX port for an application."

Post—In Internet messaging, such as email or newsgroups, it is a single message entered into a network communications system for others to see. For example, a message displayed on a newsgroup, mailing list, or discussion board is a post. It can also be used as a verb, as in "post a message to the mailing list or on the newsgroup."

PPP—Stands for "Point to Point Protocol." It is the Internet standard for dial-up connections. PPP is a set of rules that defines how your modem connection exchanges packets of data with other systems on the Internet.

PPP is addressed in RFC-1661, which can be viewed at:

Protocol—In computing, a protocol is a set of guidelines or standards by which servers and applications communicate. There are many different protocols used for many different purposes, for example, TCP/IP, SLIP, HTTP, POP3, SMTP, IMAP, FTP, and so on.

Registry—A database used by Microsoft Windows to store configuration information about software installed on the computer. This includes things like user settings, file extension associations, desktop background, color schemes, and many others. It has the following six parts:

HKEY_User—Stores user information for each user of the system.

HKEY_Current_User—Preferences for the current user.

HKEY_Current_Configuration—Stores settings for the display and printers.

HKEY_Classes_Root—File associations and OLE information.

HKEY_Local_Machine—Hardware, operating system, and installed application settings.

HKEY_Dyn_Data—Performance data.

When programs are installed on your computer the installer usually writes some information to the registry automatically. You can manually edit the registry, however, by using the regedit.exe program that is built in to Windows. But, you should exercise extreme caution when doing this because altering the wrong setting in the registry could cause your computer to function improperly, or not at all.

RFC—Request For Comments is the name of the result and the process for creating a standard on the Internet. Each new standard and protocol is proposed and published on the Internet as a “Request For Comments.” The Internet Engineering Task Force (IETF) facilitates discussions on the new standard and eventually it is established. In spite of the fact that the standard is established and no further “comments” are “requested,” the standard still retains the “Request for Comment” acronym along with its identifying number. For example RFC-822 (now superseded by RFC-2822) is the official standard, or “RFC,” for email. However, those protocols that are officially adopted as “standards” do have an official standard number associated with them that is listed in the Internet Official Protocol Standards document (which itself is STD-1 and currently RFC-3700). You can find RFCs on the Internet at many locations but the authoritative source is The RFC Editor, located at

The Internet Official Protocol Standards document is located at:

RTF—Rich Text Format is a universal file format developed by Microsoft that is supported by nearly all word processors. In contrast to plain text format, RTF enables you to retain formatting, font information, text color, and so on. The file size of RTF files can be very large when compared to other file formats such as Word 2000's document format (*.doc) and Adobe PDF.

Server—A computer, or program, that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software, such as an SMTP server, or a machine on which the software is running. A single server machine could have many different server programs running on it concurrently. For example, your network's server might be running a web server, email server, FTP server, fax server, and others all at once.

SMTP—An acronym for Simple Mail Transfer Protocol. It is the primary protocol used to send email on the Internet from one server to another or from a client to a server. SMTP consists of a set of rules for how a program sending mail and a program receiving mail should interact. Once a server has received email via SMTP it is usually stored there and can then be retrieved by a client via the POP, IMAP, or other protocol.

The SMTP protocol is addressed in RFC-2821, which can be viewed at:

Spam—Junk mail on the Internet. "Spam" is most commonly used to refer to unsolicited bulk email, although it is often used to refer to any unwanted email in general. A "spammer" will obtain hundreds, thousands, or even hundreds of thousands of email addresses from various sources and then "spam" the list with a message or solicitation. "Spam" can, however, be used to refer to a newsgroup or discussion board posting as well, when the posting is some unwanted or unrelated advertisement for a product or web site.

Spam is quickly becoming a serious problem on the Internet, tying up a great deal of time and server resources. And because spammers oftentimes use various techniques to attempt to mask the origin of the message—such as "spoofing" their addresses to appear to be someone else or attempting to relay the spam covertly through multiple mail servers—preventing it can be a challenge. Alt-N Technologies' MDaemon server is equipped with a number of features designed specifically to aid in fighting spam, such as: DNS Black Lists (DNS-BL), IP Shielding, IP Screening, Relay Control, and others.

The origin of using the term "Spam" to refer to junk email is debated, but it is generally accepted that it comes from a popular Monty Python sketch in which the word "spam" is repeated over and over and periodically accompanied by Vikings singing, "Spam spam spam spam, spam spam spam spam…" However, it may simply be a disparaging comparison to the trademarked Hormel meat product of the same name—everybody gets it at one time or another, but does anyone ever really ask for it or like it?

TCP/IP—Transmission Control Protocol/Internet Protocol (TCP/IP) has been described as the foundation of the Internet. It is the basic suite of communication protocols used on the Internet to connect hosts. It is the most commonly used protocol on Local Area Networks as well. It is a two-layer system, the topmost layer being TCP, which manages the disassembling and assembling of files into packets for transmitting over the network. IP, which is the lower layer, handles the addressing of the packets so that they get to the proper destinations. TCP is addressed in the following RFC-793. IP is addressed in RFC-791. These RFCs can be found at:


IP –

Telnet—A command and program used to log on to Internet sites that support Telnet access. The Telnet command gets you to the logon prompt of the Telnet server. If you have an account on that server, you can access your permitted resources such as your files, email, and so on. The downside of Telnet is that it is a command line program that uses Unix commands.

The TELNET protocol is addressed in RFCs 854-855, which can be viewed at:

Terminal—A device that allows you to send commands to a remote computer. A terminal is a keyboard, display screen, and some simple circuitry. Oftentimes, however, personal computers are used to "emulate" terminals.

Tiff—An acronym for Tagged Image File Format. It is a graphics file format created to be a universal graphics translator across multiple computer platforms. TIFF can handle color depths ranging from 1-bit to 24-bit.

UDP—User Datagram Protocol (UDP) is one of the protocols that make up the TCP/IP suite of protocols used for data transfers. UDP is a known as a stateless protocol because it doesn't acknowledge that packets being sent have been received.

UDP is addressed in RFC-768, which can be viewed at:

Unix—Unix, or UNIX, is an operating system created by Bell Labs in the 1960s. Designed to be used by many users at the same time, it is the most popular operating system for servers on the Internet. There are now many different operating systems based on UNIX such as Linux, GNU, Ultrix, XENIX, and others.

URL—Every file or server on the Internet has a Uniform Resource Locator (URL). It is the address that you enter into your web browser to get to that server or file. URLs cannot have spaces and always use forward slashes. They have two parts separated by "://". The first part is the protocol being used or resource being addressed (for example, http, telnet, ftp, and so on) and the second part is the Internet address of the file or server (for example, or

Uuencode—A set of algorithms for converting files into a series of 7-bit ASCII characters for transmission over the Internet. Although it stands for Unix-to-Unix encode, it is no longer exclusive to UNIX. It has become a universal protocol used to transfer files between different platforms. It is an encoding method commonly used in email.

WAN—A WAN, or Wide Area Network, is similar to a Local Area Network (LAN) but is usually spread across multiple buildings, or even cities. WANs are sometimes composed of smaller LANs that are interconnected. The Internet could be described as the biggest WAN in the world.

Zip—Refers to a compressed or "zipped" file, usually with the ".zip" file extension. "Zipping" is compressing one or more files into a single archive file in order to save space for storage or to facilitate faster transfer to another computer. To use a zip file, however, you'll need to unzip it first with the appropriate program such as PKZIP or WinZip. There are multiple compression/decompression utilities available—both shareware and freeware—from many sites on the Internet. Hopefully you won't have to unzip the utility before you can install it.