Microsoft Outlook User-Agent string ?!?

New Contributor

Hello everyone,


First post here :)


I ran into the user-agent string below and was wondering where it came from.

Is it somehow related to Office365? 

It would be very helpful to know which application will generate such a UA and in which scenario.


Sample UA:

Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; Microsoft Outlook 16.0.9126; Microsoft Outlook 16.0.9126; ms-office; MSOffice 16)




4 Replies

It's Outlook :) You see all the additional "browser" strings there because Outlook communicates with the server via the MAPI/HTTP protocol.

Thanks for the prompt response!!
Could you describe the scenario in which this UA will be generated?
I am trying to figure out the scenario here.

For example, I have an email which part of its content includes a URL to my website.
When I click the link, it opens Chrome and my site loads.
Looking at the logs I do not see the Outlook section in the UA string, but the default Chrome UA.

Thanks again,
best response confirmed by aviamsi (New Contributor)

Not sure what you mean exactly, are you looking at your website logs and seeing the user agent string there? If so, it's most likely because of RSS subscription that someone has configure via Outlook. Or maybe Outlook fetching an image or other file attached to an email, which is hosted on your site.

Yes, you got my question right.

I was trying to reproduce this behavior (to take the action needed to make this UA string appear in logs).

Just trying to understand the flow.


I will setup my Outlook to fetch a RSS feed and will check whether I see this UA in my logs.


Many thanks for the great help on this.