This article applies to:

Outlook 2016

Office 365

Message Header Analyzer



User reports that an e-mail message was delivered with a delay and as a first troubleshooting step, you need to figure out where exactly did the congestion occur.



The information about the exact congestion location is quite easy to get from the e-mail message header.  Along the e-mail delivery route, every e-mail server which processes the message, stamps its information into the message header, along with the date/time information. The header in its native format is fairly hard to read therefore I am going to show you how to use Message Header Analyzer tool. The tool is free and comes in two forms: as an Outlook add-on and as a web based tool. We are going to cover both in this article.


Using the Message Header Analyzer as add-on in Outlook 2016

If you are an Office 365 user with Outlook 2016 you can install the Message Header Analyzer Add-on from the Office Application Store. To access the store click on the Get more apps button on the right


In the store, search for message header analyzer


Click on the Message Header Analyzer icon to install.


Click Add.


Sign into your Office 365 account if required.


Select Install.


Once installed, the Message Header Analyzer will show in the list of your Office add-ins. If you are an administrator you can also provide this for all of your users.


The cool thing about Outlook Add-ins in Outlook 2016 is that the same plugin works both with Outlook client as well as Outlook Web App.

So now that you have the plugin installed, it will show up on the plugin bar. So all you have to do in order to analyze an e-mail is to select the message and click the Message Header Analyzer button.


It works the same in Outlook client: open the message, click Message Header Analyzer and you get the message header in a nice and readable table format showing exactly where the congestion point is and how long the delay was. So in this specific case we can see that the delay occured  between 2 Exchange online servers hosted by Microsoft in their Vienna and Dublin data centers.



Using the online version of the Message Header Analyzer

There might be situations where you can’t use the Outlook plug-in. For example you have an older version of Outlook which does not support the latest add-ins,  or if your administrator has blocked installation of office add-ins via Group Policy.

In that case you manually extract the message header in Outlook and analyze it with the online version of the Message Header Analyzer.

Open the message you want to analyze and select File from the menu.



Select Properties



Right click internet headers field.


Click Select All


Click Copy.


Open a browser and go to the Microsoft Remote Connectivity Analyzer page under

Paste the header information into the analyzer.


Click Analyze.


And again you are presented with the analyzed information in a clearly readable table format with calculated delivery times.



Beside delivery information Message Header Analyzer also extracts information stamped by antivirus or antispam software which you can use in case you need to determine if the e-mail was scanned for viruses, or why a message landed in a junk mail folder.

Dejan Foro