how do I find background information on someone if I only have their
email address and not their name.  For example, an unsolicited email
from an unknown person which provides only his or her email address. 
I would like to find some background information on the person to see
if they are legitimate.

Hi there,

I know of a number of techniques that can help you with your quest,
but keep in mind these two things:

1) Almost all spam uses false email addresses. 

2) To find out who is behind an email address, they need to have used
it on the web somehow. Approximately half the email addresses I
investigate have only been used for private correspondence, and
nothing else. These people remain anonymous.


Validate!
---------

Before doing anything, check to see if the email address is valid, and
not just made up. Two good places to do this are:

Verify Email
http://www.verifyemail.com/

Schwarzl
http://www.schwarzl.com/mailcheck.html


Google!
-------

Just enter the email address in Google and search. If it appears on a
web page (forums, guestbooks, homepages), Google will probably find
it.


Email Directory
---------------

The best for reverse email searches is:

SmartPages
http://smartpages.infospace.com/_1_2LGPTTE03TSGRZG__yp.smart/reverse.htm

Entering @host.domain will return a list of all users in that domain.
Or joebloggs@ will return all listings starting with those characters.


Usenet
------

Google Groups is a massive archive of Usenet postings going back many
years. All postings have an email and name attached to them. If you
find the email address there, you can possibly learn the person's
name, and hobbies or interests. Enter the email address in the Author
field:

Google Groups Advanced Search
://www.google.com/advanced_group_search?hl=en


ISP home pages
--------------

Many email addresses come free with an ISP account. AOL would be the
most famous example. Often they get a free webpage as well, and the
name of the webpage tends to be the same as the email.

joebloggs@aol.com could have a webpage at members.aol.com/~joebloggs

The easiest way to check is using Google. In the domain field, enter
the ISP name, such as aol.com. In the top search box, enter the user
name, such as joebloggs. This could find their homepage.

Google Advanced Search
://www.google.com/advanced_search


Internet Messengers
-------------------

These are hugely popular, and have directories of their users, which
you can search by email address. ICQ, Yahoo, Odigo and AOL have this
ability. Unfortunately MSN doesn't.

Reverse Messenger Search
http://searchenginez.com/reverse_messenger.html


Search Strategy
---------------

This is something I do everyday, for a website that specializes in
people finding using web resources.


Best wishes,
robertskelton-ga

very thorough