Whether you write in-house documentation, software documentation for wide distribution, security or system administration articles for TR, or just satire, you may find yourself making up an email address on the spot. Unfortunately, sometimes people actually use our example addresses, and sometimes those examples aren’t as unique as we might think. For all example URL and mail addresses use "example.com", "example.net", "example.org", "example.edu", for example:
E-mail address harvesting bots and Web spiders, pranksters, people who misunderstand your satire and are maybe a little stalkerish in their devotion to you, and even people honestly just trying to follow the directions of your otherwise excellently written documentation or howto may pick up an example address in what you write.
If that address happens to correspond with an email address used by a real, live human being, the person could conceivably receive spam, hate mail, or confusing test email messages as a result of your poor choice in example email address. There have even been cases of people following directions in a howto and accidentally sending confidential information to someone that actually uses the example e-mail from the howto.
It is specifically to address this sort of problem that RFC 2606 was published by the IETF (Internet Engineering Task Force). Of particular interest when dealing with e-mail examples is Section 3, which addresses the use of second-level domain names with existing, real-world top-level domains in examples.
The three second-level domain names have been reserved by the Internet Assigned Numbers Authority (IANA) for use as example domains are:
The Internet Assigned Numbers Authority is the entity that oversees global IP address allocation, root zone management for the Domain Name System (DNS), media types, and other Internet Protocol related assignments. It is operated by the Internet Corporation for Assigned Names and Numbers, better known as ICANN. Internet Corporation for Assigned Names and Numbers is responsible for managing the assignment of domain names and IP addresses. ICANN's tasks include responsibility for IP address space allocation, protocol identifier assignment, top-level domain name system management, and root server system management functions. To date, much of its work has concerned the introduction of new generic top-level domains (TLDs). The technical work of ICANN is referred to as the IANA function. ICANN's primary principles of operation have been described as helping preserve the operational stability of the Internet; to promote competition; to achieve broad representation of global Internet community; and to develop policies appropriate to its mission through bottom-up, consensus-based processes.
When presenting example e-mail addresses, or any example domain names, these are generally your best options. There are also reserved example TLDs s (Top Level Domains) specified in RFC 2062, if you need them.
Section 5 of RFC 2062, Security Considerations, has this to say:
Confusion and conflict can be caused by the use of a current or future top level domain name in experimentation or testing, as an example in documentation, to indicate invalid names, or as a synonym for the loop back address. Test and experimental software can escape and end up being run against the global operational DNS. Even examples used "only" in documentation can end up being coded and released or cause conflicts due to later real use and the possible acquisition of intellectual property rights in such "example" names.
The reservation of several top level domain names for these purposes will minimize such confusion and conflict.
In Russia, the test.ru second-level domain is reserved for use in examples. You can also use this domain as a place to test your applications during development.