Find People by Email
Nearly everyone's familiar with reverse telephone searches -- the process through which you can take a telephone number (whether jotted on a notepad at some time in the past, or taken from your answering machine's caller ID), and determine whose name and address the telephone number is registered to. To find people by email, you use a rather similar process -- starting with an email address and using it as the basis for a search which will hopefully lead you to some data about who the person is outside the electronic world.
One of the questions you need to answer when you're thinking about how to find people by email is whether you really need this information. For example, you may be able to track down the sender of a specific piece of spam, but is it really worth your time, effort, and possibly expense to do so? You already know that the message is spam, so there is really nothing more to be done with it except to mark it is as spam so that your email filters will catch future messages from that source before you see them, and then delete it.
The next question you need to ask yourself is whether you have more direct options to find the people you want to find other than using email. Asking mutual acquaintances, checking with a place of employment, or just looking in the telephone book can often let us find a person more easily than trying to find them by a reverse email search.
Once you've decided that there's nothing for it other than to try to find people by email, you need their email address in order to start your search. Typically, you already have it -- getting a message from them is the most usual reason you want to discover who they are and where they live in the first place. When you're beginning your search, make sure you've got the exact spelling of their email address written down clearly where you can see it. This sounds ridiculously easy -- but it is actually a very important step, because there are so many email accounts with very similar names, and you don't want to track down the wrong person and draw the wrong conclusion as a result.
Most "free" email directory searches are actually previews of full, paid searches from commercial directory sites. The free search will give you a little information -- enough to whet your appetite -- but you will need to pay more in order to see the complete information about the email's sender (assuming any information is available at all). However, this 'teaser' information may be enough to let you judge the validity of the email -- or at least decide whether it's worth paying the fee to see the person's real life identity and location. Apply common sense and remember your needs. If you need the physical address of the person, then paying the fee to get it is the logical next step when you find people by email. If finding out that they're in the city they claim to be in is enough for your purposes, then the free data may be all you need.