Office 365 Exchange Admin Center Spamfilter settings vs. Outlook 2016 Client Junk-Mail settings?

Not applicable

How are the two areas

  • Office 365 Spam filter settings in Exchange Admin Center
  • Outlook 2016 Junk-Mail settings

related to each other? Are they "interconnected" with each other? Or are they totally independent?


For example,

  • Which rules take precedence, and when?
  • What happens when a user blocks a sender in his Outlook. Is that kept local in his profile? Is this blocking "shared" with the Exchange server in Office 365?
  • What happpens when a user selects a message in the Outlook 2016 Junk-Mail folder and defines it as "not Junk"?
  • If the Office 365 spam filter settings deliver junk/spam to the junk-mail folder, and Outlook 2016 does the same, the result is emails in the junk-mail folder that origin from two different mechanisms. Am I correct?


Moreover, when I use quarantine in the Exchange Server Spam filter settings, with user notification, the user receives regularily an email where he can release a message from the quarantine into his inbox. There is also an option like "Report as not Junk" or similar. The explanation in the message tells us that this option will report this message as not junk to Microsoft.


What exactly is Microsoft doing with these messages? I would suppose they analyse it and feed the results somehow into the algorythm which "finds" spam in the future. I would be interested in the details of that process.


Is something similar happening when a user mark a message as "Not Junk" in his Outlook 2016 junk folder? Or is that something totally local and user based?





4 Replies

There's an extensive documentation available on this, I'd strongly recommend that you read it first, then come back with any unclear details. In a nutshell, everything server-side acts first, but the client-side settings can potentially "override" the verdict. The allowed/blocked sender list is kept in the user's mailbox. Outlook will inform you "who" moved the message to the Junk folder by an "information tip".

Hello Vasil,

Thanks for your reply.


Yes, you are correct. There is a lot of information to read on this matter, but it's 

either Outlook related

or Office 365/Exchange related


I have yet to find a documentation which describes the overall approach on AntiSpam/Anti-whatever with all the Tools and possibilities of the Microsoft Portfolio. That is actually what I am looking for. 


The questions I am faced with are always alike: Why was message X put in Spam folder? Why was message Y not put in quarantaine? .. and variations of those. 


For me as an admin for several customers with different levels of understanding the IT world, it's a challenge to be able to explain users why a certain message was junked or not. 


Your nutshell confirmed most of my suspicions. Thanks.

Nonetheless, if you could point me to the extensive documentation which explains the combined workflow of all involved parties (server, client, forefront, microsoft clearing center, etc.) that would be great.


And if you could give me a hint on that "information tip" you mentioned?


Many thanks





best response

You can see examples of the information bar in this article:


The bulk of the processing is always done on the server side, so the EOP documentation should cover almost all the details. You can also take a look at some of the detailed sessions from Ignite, for example this one: or

Microsoft Exchange Online Protection (EOP) is the mail filtering component for Microsoft Office 365 mailboxes, but can also be used to protect on-premises ma...
Learn how Microsoft Office 365 protects its customers against rapidly growing Spoof, Phish, Malware and Spam attacks. Get actionable insights for InfoSec as ...


I will save this article as a reference for me. Way cool.

Many thanks @Vasil Michev !