What Is an Email Message-ID and How Do I Find It?

By Geoff McQueen
Founder & CEO
Apr 28 2023 read

All emails have a unique fingerprint called a Message-ID. There are different ways of locating this identifier in various email clients. 

In this video, we show you how to find a Message-ID in Gmail, Outlook or iCloud Mail. For more details and email client options, read our walkthroughs below.

Jump to your email client:

What Is an Email Message-ID?

The Message-ID is an identifier that your mail server adds when it sends your email. The Message-ID looks a bit like a long and cryptic email address. Here's an example for an email sent from Gmail:

Message-ID: <CAKBqNfyKo+ZXtkz6DUAHw6FjmsDjWDB-pvHkJy6kwO82jTbkNA@mail.gmail.com>

The text after the @ symbol generally refers to the server that’s sending the email out to the world on your behalf. The part before the @ symbol is a unique key or identifier according to that mail server. This combination creates a unique fingerprint for every email message in the world — approximately 347 billion a day!

While Message-IDs are necessary, they're not so useful for us as users, so they're normally hidden way in your email client. 

Finding the Message-ID in Apple Mail

To find the Message-ID in Apple Mail, open the specific email, then click the “View” menu at the top of your screen. Hover over “Message” and select “Raw Source” from the secondary menu that pops up to the right.

The source of the message will appear in a new window.

Copy and paste the Message-ID in the third line from the top.

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Finding the Message-ID in Gmail

Finding the Message-ID in Gmail is pretty easy. Open the email you want, click on the Down arrow to open more options on the righthand side, then click “Show original.”

A new browser tab or window will open with the "source" of the email message. 

The information you're looking for is the in the first line at the top, labeled Message-ID. To grab the Message-ID, all you need to do is copy and paste from this screen.

Finding the Message-ID in Office365

Finding the Message-ID in Office365 requires a couple more steps than the first two.  

Open the message you want, click on the options button at the top right in the viewing pane, and then click “View original message.”

Finding the Message-ID in Office365

You'll now have a pop-up window open, which will show you the same message with additional icons across the top. Click the one that looks like an email with a sheet of paper in front of it.

Finding the Message-ID in Office365 - Popup

This will then load up the "headers" in a pop-up window. Note that you'll probably have to scroll a bit to find the Message-ID. When you find it, copy and paste.

Finding the Message-ID in Office365 - Message Details

Finding the Message-ID in Outlook 2007 (and earlier)

In early versions of Outlook, you can find the Message-ID from the Message Options screen. There are two ways to get to Message Options:

Method 1: Right-click on List

Finding the Message-ID in Outlook - Message Options from Right-Click on List

Method 2: Arrow in on View

Finding the Message-ID in Outlook - Message Options from arrow in on View

Once you're looking at the Message Options box, you'll want to look at the “Internet headers” section and scroll down until you find the Message-ID header. Copy and paste this line.

Finding the Message-ID in Outlook - Message Options

Finding the Message-ID in Outlook 2010

Microsoft changed things up in Outlook 2010 and made the Internet headers window harder to find.

Open the email message in its own window by double-clicking on it. Once there, click on File (A) in the top left. Next, click on Info (B) and then Properties (C).

Finding the Message-ID in Outlook 2010

With Properties open, scroll to the bottom of the window and look for “Internet headers.” Then, scroll within that box to locate the Message-ID, which you can copy and paste.

Finding the Message-ID in Outlook 2010 - Properties

Finding the Message-ID in Outlook Web Access

In Outlook Web Access 2007 (or later), start by opening the email message and clicking on the Message Details icon (the three dots).

From there, you'll see a pop-up box just like in Office365. Click “View message source.”

When the message source pops up in a separate window, scroll until you see Message-ID. Select, copy and paste.

Note that previous versions of Outlook Web Access did not provide any way to access email headers.

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