The Internet has evolved dramatically in the last 25 years. But one aspect of online interaction has remained largely untouched. I am talking about the humble email address.

Despite the growth of web-based phone and video and the dominance of social media, the importance of the email address has actually increased. Indeed, the primary way to log into these other burgeoning communications channels is most commonly to use your email address as your username.  After all these years, it’s easy to take it for granted. But from a data perspective, it’s worth taking a few minutes to explore some of its hidden value.

First, an email address is a unique identifier. Yes, many people have both a personal and business email address, but those email addresses are role-based, so they generally remain unique within a given role. Moreover, many data aggregators have been busy building databases of individuals and all their known email addresses, making it easy to resolve multiple email addresses back to a single individual. 

Unique identifiers of all kinds are extraordinarily important because they provide disambiguation. That means that you can confidently match datasets based on email address because no two people can have the same email at the same time.

But email addresses aren’t just unique identifiers, they are persistent unique identifiers. That means that people don’t change them often or on a whim. Further, unlike telephone numbers, email addresses tend not to be re-issued. That’s because businesses work hard to avoid re-issuing email addresses and as to personal emails, they are typically very cheap to keep and a big hassle to change, resulting in a lot of stability.

 Let’s go a step further: email addresses are persistent, intelligent unique identifiers. At least for business use, email addresses are not only tied to a particular company, the company name is embedded in the email address. And again, data aggregators have been hard at work mapping domain names to detailed information on the companies behind them. That’s why an increasing number of B2B companies actually prohibit people from signing up for such things as a newsletter using a personal email address. A personal email address (e.g. arty1745@gmail.com) tells them little; a business email address (e.g. jsmith@pfizer.com) readily yields a wealth of company demographics with which to both target promotions and build audience profiles. Indeed, even the structure of email addresses has been monetized. There are, for example, companies that will append inferred email addresses based on the naming convention used by a specific company (e.g. first initial and last name). It’s also interesting that the top level domain can tell you the nature of the organization (e.g. “.org”), the country where it is operating (e.g. “co.uk”), and even the nature of its business (e.g. “.edu”).

 The unique format of the email address also adds to its value. While the length of an email address will vary, the overall pattern with the distinctive @ sign makes it easy to harvest and extract. It also makes it possible to link text documents (perhaps academic papers that include the email address of the author) to data records.

 Sure, email addresses have real value because they can put marketing messages under the noses of prospects, but to a data publisher, email addresses are worth a whole lot more.