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One Step Ahead: Almanac Security Tips - 2014

In each issue, Penn's Journal of Record, The Almanac publishes helpful tips and hints for dealing with information security and privacy matters. This page is a collection of all those published thus far.
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Table of Contents (view all)

9 things tagged with email.

E-mail Headers: Getting the Full Story
A Reminder About Free Wireless Networks
Several Types of Risks in Email
Quality Assure: Who is Getting Your E-Mail
Electronic Group Mailing Lists: Consider the Privacy Risks
Personalized Email Scams
Don’t Keep Email Around Too Long
Spam Filtering
Does Your E-mail Sometimes Smell "Phishy"?

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Tagged with spam , email

2009-02-10 - Almanac Vol. 55, No. 21

E-mail Headers: Getting the Full Story

Whether it's common spam or messages that are actually threatening or disturbing, Penn Information Security is often asked about how to identify the sources and senders of troublesome e-mail. Because e-mail is so easily forged, it's usually the case that conclusive identification of who and where a "bogus" message came from is not possible. There are instances, though, where the information contained in the message headers can indicate or strongly suggest the source. Similar to the information found on the envelope in which a postal letter is sent (address, return address, postmark), e-mail message headers are sort of an "electronic envelope" that may contain literally dozens of bits of data about how the message was sent.

Most ordinary e-mail users are familiar with only a handful of these headers — "To:," "From:," "Cc:," "Subject:," "Reply-To: — because most e-mail programs consider these the only ones the user is really interested in and "helpfully" hides the rest from view under normal circumstances. With few exceptions, though, modern e-mail programs also provide an option to display the full headers for inspection. Like the "From:" header, many of these hidden headers can be forged or manipulated, but others are very difficult to fake. For example, each message will have a series of "Received:" headers which detail the mail servers through which the message travelled, and these are extremely difficult to forge. So, if you receive what looks like a message "From: upenn team," but the headers indicate the sending server is from a ".ru" (Russia) or ".cn" (China) domain, you can be pretty confident it's not really from a Penn source.

If you're using Outlook, here's how to display the full message headers:

  1. Open the message in its own window by double-clicking the message.
  2. Select View-> Options.
  3. In the Internet Headers window, you’ll see the full headers.

For how to do this with other e-mail programs, the spam reporting service SpamCop has a very useful page at A final note: If you are ever asked to provide a suspicious or troubling e-mail message with full headers to authorities for investigation, simply using the "Forward" button will not suffice, because your server will simply replace the original headers with its own. In this instance, display the full headers along with the message body, cut-and-paste all of it into a new message and send that.


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