Understanding email headers

In diagnosing certain email problems, email headers are useful for providing additional information in relation to the email message. These can determine delivery times and the route that mail was relayed from the computer it was sent from right through to delivery.

Sometimes our support team will request that you provide email headers so we can diagnose and advise. If you wish to interpret headers for yourself, there are two online tools useful for this:

G Suite Toolbox (Google) MessageHeader

MX Toolbox Email Header Analyser


To see how to access the email headers, please visit our knowledge base guides

An example of headers are included below

Return-Path: support@letshost.ie

Delivered-To: user@example.com

Received: from lh10.dnsireland.com

by lh10.dnsireland.com with LMTP id wBA4HwxpmlueeQoAfZEuIw

for user@example.com Thu, 13 Sep 2018 14:41:32 +0100

Return-path: support@letshost.ie

Envelope-to: user@example.com

Delivery-date: Thu, 13 Sep 2018 14:41:32 +0100

Received: from [78.137.164.41] (port=45078 helo=lh6mail.dnsireland.com)

by lh10.dnsireland.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256)

(Exim 4.91)

(envelope-from support@letshost.ie)

id 1g0Rs3-002sau-9W

for user@example.com; Thu, 13 Sep 2018 14:41:32 +0100

Received: from lhsuppod by lh6mail.dnsireland.com with local (Exim 4.91)

(envelope-from support@letshost.ie)

id 1g0Rs2-0005DJ-6D

for user@example.com; Thu, 13 Sep 2018 14:41:22 +0100

To: user@example.com

Subject: Understanding E-Mail Headers

Message-ID: 5fca83217b5106a67bbe3ca5e1f58408@www.letshostsupport.com

Date: Thu, 13 Sep 2018 14:41:22 +0100

From: LetsHost Support <support@letshost.ie

Reply-To: support@letshost.ie

MIME-Version: 1.0

Content-Type: multipart/alternative

boundary="_=_swiftmailer_v4_1536846082cbb00f6d5828d3edba1fbe140958d564_=_"

X-Spam-Status: No, score=-2.9
X-Spam-Score: -28
X-Spam-Bar: 

X-Ham-Report: Spam detection software, running on the system "lh10.dnsireland.com",

has NOT identified this incoming email as spam. The original

message has been attached to this so you can view it or label

similar future email.

Please note that with mail headers these can be forged throughout the relay. Generally, these can pinpoint issues with delivery and how they are handled. The most common headers are included below for reference.

  1. From - Displays who the email is from, however please note that this can be forged

  2. Subject - This is the topic of the email content that the sender has assigned

  3. Date - The date/time when the email was sent

  4. To - The address to which the email is addressed

  5. Return-Path - The email address for return mail. Similar to Reply-to which indicates where software should send a reply when you choose to reply to the message

  6. Envelope-to - The mailbox to which this was sent

  7. Delivery-date - The date/time that the email arrives in the mailbox

  8. Received - Indicates where and what points the message was relayed through. Often used to determine if there was a delay at any of these points

  9. X-Spam-Status - If yes, then this is marked as spam. This may be used either by SpamAssassin which is included by default, our spam filter service, or by software running on your own computer (e.g. McAfee Anti-Spam)


If you require further information/assistance on this, please Open a Ticket and a member of the team will be happy to assist further.

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