Bang Path

Definition of Bang Path

Bang path is a term used in early email systems and computer networks, describing an explicit, source-based routing protocol. It comprises a sequential series of computer addresses, separated by exclamation marks, indicating the specific route that an email or data packet should take while being transmitted through the network. Nowadays, this method has been mostly replaced by the more efficient Domain Name System (DNS) and the Simple Mail Transfer Protocol (SMTP).


The phonetics of the keyword “Bang Path” can be represented using the International Phonetic Alphabet (IPA) as:/bæŋ pæθ/Here, “bæŋ” corresponds to ‘Bang’ and “pæθ” corresponds to ‘Path.’

Key Takeaways

  1. Bang Path is an older, less popular routing protocol mainly used for email transmission over the UUCP (Unix-to-Unix Copy Protocol) network.
  2. It relies on a series of nodes (‘!’ marks, known as ‘bangs’) in the email address to indicate the exact route a message should take to reach its destination.
  3. Due to its manual and human-driven nature, plus advancements in technology, it has been largely replaced by other more efficient routing methods, like DNS and SMTP.

Importance of Bang Path

The term “Bang Path” is important because it represents an early method of routing electronic messages in computer networks, specifically in the context of early email systems and Usenet.

It played a vital part in the development of the internet, as it allowed users to communicate across different networks before the establishment of more advanced routing protocols like DNS and SMTP.

Bang paths were manually constructed strings of routing instructions, depicting a series of hostnames separated by exclamation marks, which guided a message from its source to its destination.

While this system had limitations and was eventually replaced by more efficient and automated addressing schemes, Bang Path was a pioneering concept that contributed to the evolution of networked communication standards and protocols we rely on today.


Bang Path refers to a routing methodology that was once utilized heavily in the early days of the internet. Its purpose was to facilitate the process of sending messages from one user to another through a series of intermediary systems, known as relay nodes, before reaching the intended recipient. This method was critical in an era when network connectivity was relatively scarce and many computers were not part of widely interconnected networks.

The bang path essentially provided a route for the message to follow, bypassing any connectivity limitations by moving the message through a sequence of systems that were already linked. Under the circumstances, the bang path played a crucial role in connecting disparate computer networks across the globe. It enabled users to communicate with others, even if they were operating on geographically distant or technologically disparate networks.

Each step of the path utilized an exclamation mark (also known as bang) to denote the route that the message needed to follow. This notation process provided clear instructions for the relay nodes to pass the message along until it reached its intended destination. Although obsolete by today’s standards – replaced by more efficient routing algorithms and protocols – the bang path was an essential element in the formative years of the internet, setting the groundwork for the global communication networks we know today.

Examples of Bang Path

Bang Path, also known as “bang-style routing,” was used in the early days of email for transmitting messages between systems on the internet. It was a rudimentary method of routing emails through a series of intermediate nodes, with each node represented by an exclamation point, or “bang.” Here are three real-world examples of Bang Path technology:

UUCP-based Email Transmission:In the 1970s and 1980s, Bang Path was primarily utilized in UNIX-to-UNIX Copy (UUCP) protocol for exchanging emails and files between different UNIX systems. Since hierarchical Domain Name System (DNS) was not yet implemented, email messages needed to travel through a sequence of intermediate systems. For instance, a user from System A wanting to send an email message to System B would have to rely on the systems linked through UUCP and a series of “bangs” that represent each of those systems.

ARPANET Mail:Before the widespread use of Domain Name System, ARPANET, the predecessor of the internet, employed Bang Path technology for email routing. Users had to manually specify the entire route for transmitting an email message from the source to the destination. For example, “userA!system1!system2!system3!userB” would signify that the email had to pass through system1, system2, and system3 to reach userB.

Usenet News Network:Bang Path technology was also used in the early days of Usenet, a distributed discussion forum that primarily functioned on UUCP protocol for exchanging news articles and messages between the members of Usenet nodes. With no proper DNS-based structure, UUCP servers employed bang paths to route messages across networks, similar to the transmission of emails.In modern times, Bang Path has been effectively replaced by the more efficient and hierarchical Domain Name System, which simplifies routing without needing a series of intermediate nodes.

FAQ: Bang Path

What is a Bang Path?

A Bang Path is an old and deprecated form of email addressing used in the early days of the internet. It involves specifying the route to deliver a message in the address, using exclamation marks (‘!’) to separate the elements of the path. This method allowed messages to be sent across networks before the existence of the Domain Name System (DNS).

How does a Bang Path work?

A Bang Path works by listing the successive hosts the message should travel through to reach its destination. For instance, if you wanted to send an email to a user at host ‘G’, you might use the address “A!B!C!D!E!F!G!user”. The message would then be sent through the listed hosts (A to G) in order to reach the intended recipient (‘user’).

Why are Bang Paths no longer in use?

Bang Paths have largely been replaced by the more modern Domain Name System (DNS) and Simple Mail Transfer Protocol (SMTP). DNS simplifies email addressing by using a hierarchical naming system that maps domain names to IP addresses. SMTP is a standardized protocol that efficiently handles email delivery between servers. These technologies have made Bang Paths obsolete, as they offer better scalability, flexibility, and ease of use.

Can I still use a Bang Path for email addressing?

While some systems might still support Bang Paths, it is strongly discouraged to use them for email addressing. Their use can lead to delivery issues, and many modern email systems may simply reject messages using Bang Paths due to their obscurity and potential security risks.

How do I convert a Bang Path to a modern email address?

Converting a Bang Path to a modern email address is usually a straightforward process. The last element in the Bang Path is typically the username, and the previous elements make up the domain name, separated by periods instead of exclamation marks. For example, the Bang Path “A!B!C!D!E!F!G!user” would convert to “[email protected]” in a modern email address. However, due to the obsolescence of Bang Paths, it is possible that some elements in the path may no longer have corresponding domains or servers.

Related Technology Terms

  • UUCP (Unix-to-Unix Copy Protocol)
  • Email Routing
  • Store-and-Forward Network
  • Usenet News System
  • Outdated Network Protocol

Sources for More Information


About The Authors

The DevX Technology Glossary is reviewed by technology experts and writers from our community. Terms and definitions continue to go under updates to stay relevant and up-to-date. These experts help us maintain the almost 10,000+ technology terms on DevX. Our reviewers have a strong technical background in software development, engineering, and startup businesses. They are experts with real-world experience working in the tech industry and academia.

See our full expert review panel.

These experts include:


About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

More Technology Terms

Technology Glossary

Table of Contents