Accessing Email Headers
What are email headers?
Email headers contain information about every email you send and receive. Among other things, the header information can tell you exactly who an email is for, where an email is from, what the Subject line is, and how it has travelled from the sender to the recipient.
The example below shows an email sent from "firstname.lastname@example.org" to "email@example.com", with the subject line "Test email!". We can see it originated on the same server ("localhost") and appears to have been sent using the "Roundcube" webmail software. The headers also disclose the identifier "1M45CL-0000gd-HH", which can be used to trace this specific email through the mail logs.
This additional information can understandably make diagnosing a problem with your email a whole lot easier. Unfortunately, most email software hides the header information from you by default. This is because humans don't usually want to see the technical workings of their email. They just want to read the mail. All you typically see of the headers is the basic "From", "To", "Date" and "Subject" information.
So how do I view the full email headers?
Because there are so many different ways people access their email, there isn't room enough in our support section to cover every possible method of viewing your headers. The "Support" or "Help" information provided for your email software will usually tell you how to view the full headers, but if not, SpamCop also keep a comprehensive list at http://spamcop.net/fom-serve/cache/19.html