Is There One Email Directory With All Email Addresses In It?
Two major reasons that there is no email directory is because of security and control. By limiting the number of people who have access to all their email holders, they protect themselves as well as their customers from unsolicited emails of all varieties, as well as the possibility of identity theft.
Of course, the biggest reason that there is no central email directory is that any directory would have to be modified in major and time-consuming ways almost everyday. Not only do people receive or request new email addresses each day, the number of email providers increases to meet this demand. There are simply so many domain names in use at any given time that trying to publish them all in one location—even online—is next to impossible.
This does not mean, though, that you cannot find out more about an email address. In fact, since each email provider keeps an up to date email directory for their own records, all the information you could ever need probably exists somewhere, but finding it can be a challenge. A reverse email search can access private email directories.