Email Header Analyzer

When you’re having problems with email delivery, an email header analyzer can help you figure out why email providers think you’re sending spam email. We recommend using header analyzers in conjunction with Mailgun's logs to diagnose problems fast.

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What Are Email Headers?

Simply put, email headers are code that is inserted at the very beginning of an email message. Headers aren't visible in the content of your email (what you read when you get an email), but they're scanned by Email Services like Mailgun, and by inbox providers like Gmail and Yahoo.

Headers contain information about who sent the email, who the intended recipient is, and how the email was routed before it even got to the inbox.

They're also used to analyze the message for spam. Spammers use complex techniques to make the email seem legitimate, so the headers give ESPs and ISPs powerful information to help detect spam.

Each email is stamped by the MTA, or Mail Transfer Agent, with information about the recipient, time, and date. That information is stored in the email header! Email authentication information, like SPF and DKIM records, are also stored in the header, like an ID card for sending email.

Analyze Your Email Headers for Better Email Delivery

Google, Yahoo, Microsoft Outlook, and other email providers look at more than your message source content to try to determine if a message is spam. Every email also has a message header that gives important information about the message and the sender.

These fields include the From, To, Date, and Subject lines which are displayed to recipient, as well as other headers that aren’t normally displayed by the email client, like X-Report-Abuse and X-Apparently-To. You can think of those extra fields as the barcode you sometimes see on envelopes from the post office; they provide information that helps the mailbox provider handle the message properly.


Headers Prove You And Your Email Are Legitimate

Spammers can spoof the From field, so some of the most important email headers provide authentication details that prove you are who you claim you are. Mailbox providers look for SPF and DKIM headers to confirm the IP address of the sender is allowed to send emails for the domain and that the message wasn’t tampered with. Mailgun gives you the details you need to set up those records, plus a button to let you verify them.

Other message headers tell email providers you’re a responsible email sender. Every email marketing message should include an Unsubscribe link and header. Mailgun provides Auto Unsubscribe to handle this for you. If your Message ID is formatted incorrectly, Gmail can think the message is spam. Use Mailgun and let us create a properly formatted Message ID for you.


How to Use Your Header Analysis

You can use email header analysis on incoming messages to help you manage your own email list and identify problems like signups from competitors and other bad leads. The inbound routing service from Mailgun gives you all the headers in easy-to-work-with JSON.

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Improve Your Email Deliverability

Mailgun can help you make sure your emails go out with good headers and high deliverability. If you’re having problems with email delivery, our support team will help you track down the problem. Get started with a free trial now. Or check out email header services like

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to bundle together features for better deliverability. For businesses that send over 100,000 emails.

Other Features

Explore Beyond Email Headers

Mailgun has a variety of features for companies to improve their email headers.

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