As of 2009, anonymous emails are still sent out frequently over the Internet. If you'd like to know more about the mystery senders of some of the emails you've received, there are a few simple steps you can take.
Check the sending email address to see if you recognize it. Sometimes, people send emails with fake or anonymous names, but forget to change their sending email addresses. In this case, you can easily determine who sent your "anonymous" emails.
Look at the header information on the email. This is disabled by default in most email browsers, but can be viewed easily with a few quick menu selections. In Outlook Express, for example, go to the "View" menu and click on "Options" and you should see an option for viewing full headers in an email.
Scan through the headers to look at the xheader information next to "Received:" There should be two such lines, the first from your own mail server and the second from the originating mail server. In some cases, you will find that this second email server is a domain you recognize, and the sender of the email can be deduced.
Check the IP address in the xheader next to the second "Received: from" line. Even if you don't recognize email addresses and servers, IP addresses are rarely masked. The actual IP address used by your email's creator should be right there for you to see.
Look up the IP address using the tool in Resources. This will give you all the public information for the registrant of that IP address, which may allow you to deduce who is sending you anonymous emails.
If you are receiving anonymous spam, simply mark it as spam and don't worry about finding the sender.
Anonymous threats are sometimes serious. If you receive them repeatedly, notify the police.