Every email you send will have email headers. Email headers were designed to share information about the email that was sent, so the receiving email server can validate, authenticate,
interpret, and implement certain functionality based on the email headers that exist. Some email header are completely informational, some are required,
and some are important to have in order to have your emails delivered properly.
If you're sending an email, it must contain the following headers (
from, date, to, message-id, and subject). Keep in mind, that the value associated with some of these email headers can be blank, but they must be present and should only appear 1 time.
Other others like
"received", are added by the receiving email servers, and can appear multiple times as your email is transferred to different places, before reaching it's final destination.
Email headers like
"dkim-signature" is an authentication type header that allows the receiving mail server to validate if the message was tampered with.
The
"List-Unsubscribe" header is optional that email senders can include in the header portion of the messages they send. The receiving mail client then displays the information in this header to allow the user to easily un-subscribed to the email newsletter or communication
If you ever wondered what headers are on the emails you send out, you can use our
Mail Tester Pro Tool it will display all the header information contained within the email you sent. It will also do a basic validation check to ensure all the required headers are present and in the right quantity. Below is the sample section of the report concerning header information. The entire report is based off validating and authenticating information found in the headers.
Read out next blog in the Mail Tester Series:
Mail Tester - Understanding MX Records, PTR Records, and Reverse PTR Records AKA rDNS.
The Mail Tester Pro Report - Header Information Section
| Publication: RFC 822 |
| Header Information |
| Name |
Value |
| return-path |
<mailtest@unlocktheinbox.com> |
| received |
from mail.unlocktheinbox.com (mail.unlocktheinbox.com [168.144.32.46]) by unlocktheinbox.com with SMTP; Thu, 5 Apr 2012 22:56:19 -0400 |
| dkim-signature |
v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=unlocktheinbox.com; s=secure; h=Content-Transfer-Encoding:Content-Type:MIME-Version:To:From:Subject:Date:Message-ID; bh=g3zLYH4xKxcPrHOD18z9YfpQcnk/GaJedfustWU5uGs=; b=V9/t0UnN278ioLmuMkylTQYQnYs3Si59CEMbSkgoxBxOgTL5A1J7GwZLH2POnGvVN107izPGI5ekUxONZRG19a+F/8owB675w4kc6ragbvNX3Op5MFBquy0WlbLL5GlJ; |
| domainkey-signature |
a=rsa-sha1; q=dns; c=nofws; s=secure; d=unlocktheinbox.com; h=Message-ID:Date:Subject:From:To:User-Agent:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:Importance; b=dSMhrkgARCXZqVdkDq/1/irPFgXoAUllgC0elg5PUAMsWHp8yQ9sq
JERhAlJvrlJ49Mp8cfba6oYCAGpiP0uP0c3TASDsRvpMOjP+aQBOri2A/
ic2UDQ2LALXJn0QoUs; |
| received |
from localhost.localdomain ([127.0.0.1] helo=mail.unlocktheinbox.com) by
mail.unlocktheinbox.com with esmtpa (Exim 4.69) (envelope-from) id 1SFzLW-00013Y-MV for mailtest@unlocktheinbox.com; Thu, 05 Apr 2012 22:55:54 -0400 |
| received |
from 168.144.32.46 ([168.144.32.46]) (proxying for 168.144.32.46) (SquirrelMail
authenticated user mailtest@unlocktheinbox.com) by mail.unlocktheinbox.com with HTTP; Thu, 5 Apr 2012 21:56:18 -0500 |
| message-id |
<cafd4302c5235420@mail.unlocktheinbox.com> |
| date |
Thu, 5 Apr 2012 21:56:18 -0500 |
| subject |
This is a test of Unlock The Inbox Mail Tester. |
| from |
"Mail Tester" <mailtest@unlocktheinbox.com> |
| to |
mailtest@unlocktheinbox.com |
| user-agent |
SquirrelMail/1.4.22 |
| mime-version |
1.0 |
| content-type |
text/plain;charset=iso-8859-1 |
| content-transfer-encoding |
8bit |
| x-priority |
3 (Normal) |
| importance |
Normal |
| x-antiabuse |
This header was added to track abuse, please include it with any abuse report |
| x-antiabuse |
Primary Hostname - mail.unlocktheinbox.com |
| x-antiabuse |
Original Domain - unlocktheinbox.com |
| x-antiabuse |
Originator/Caller UID/GID - [47 12] / [47 12] |
| x-antiabuse |
Sender Address Domain - unlocktheinbox.com |
| Publication: RFC 5322 |
| Header Counts |
| Name |
Count |
Result |
| From |
1 |
Passed |
| Date |
1 |
Passed |
| To |
1 |
Passed |
| CC |
0 |
Passed |
| BCC |
0 |
Passed |
| Reply-To |
0 |
Passed |
| In-Reply-To |
0 |
Passed |
| Messsage-ID |
1 |
Passed |
| Subject |
1 |
Passed |
| References |
0 |
Passed |
| Sender |
0 |
Passed |