What Kind of Metadata is in an Email?
Email Meta DataThe "STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES," was published in August, 1982. More familiarly known as RFC 822, this standard describes twenty-five fields that Internet emails may contain.
Below is an abbreviated version of RFC 822 showing the valuable data elements available if you have access to the electronic files.
Bcc Recipients whose names aren't visible to other recipients. (Bcc names will never be seen on a printout unless it's printed from the sender's files.) Optional -- and rarely seen on printouts.
Cc Additional recipients other than the primary recipient, if any. Optional
Comments Textual comments that don't affect message contents. Optional
Date The date on which the message was sent. Required
Encrypted Methodology used to encrypt the message. Optional
From Sender's identity. Remember that the sender may not be a human being, but could be a computer sending out email to a list. Required.
Continued Email Metadata InfoIn-Reply-To Identifies previous email answered by this message. Optional
Keywords Keywords separated by commas. Optional
Message-ID Unique machine readable ID for this particular email. Can be of vital importance in authenticating email. Optional -- but almost always used. Does not show up on ordinary printouts from an email client.
Received Shows the time when a message was received by the intended recipient and the entire route taken from the sender's machine to the recipient's, which often includes a great many stops along the way. This information is vital to authenticating email and in determining if there are other machines that you should be examining. Optional, but almost always used. Email servers from the beginning of the route through the end add their information automatically.
References Identifies previous email referenced by this message. Can sometimes be useful in authentication and determining whether the adverse party has produced all that they should. Optional
Email Metadata Part ThreeReply-to The mailbox to which responses should be sent. Usually the same address as the sender, but sometimes not. Optional -- but many email clients include it.
Resent-bcc The same as Bcc, but applies to messages that have been forwarded. Optional
Resent-cc As above with application to Cc. Optional
Resent-date As above, with application to Date Optional
Resent-From As above with application to From. Optional
Resent-Message-ID Same as above with application to Message-ID. Optional
Resent-Reply-to Same as above with application to Reply-to. Optional
Resent-Sender Same as above with application to Sender. Optional
Return-Path Address and route back to originator of email. Optional
Sender The address of the user who sent the email. Required
Subject The subject of the email Optional
To Primary recipients of the email Required
X- Prefix for user created labels. Optional