Third Party Spam Filter

Copper Contributor



When using third party tooling for Spam Filtering in O365 (Sender > Spam Filtering > O365), what are the recommended settings for the out of the box 0365 spam filter? Should it be left as standard, or can/should spam filtering be disabled altogether in O365?

3 Replies

This article talks about this scenario:


Hooking up additional spam filters in front of or behind Office 365


"If you are going to use a third-party to do spam filtering, we recommend you do it this way: Using a third-party cloud service with Office 365. That points your organization’s MX record at EOP so that we are in front and the third-party is behind us. Many add-on services recommend you do it this way because they assume you have a spam filter in front of their service. "


Not sure if that helps but that's what I managed to find.


Hi Cian, 


Thank you for the response. I read the article; however, would I be right in saying Office 365 will check the email again after the third party spam filter has given it the all clear? There appears to be no option to disable the O365 spam filter. Or should the O365 spam filter settings be set to default and this shouldn't cause an issue?

best response confirmed by Jack McNay (Copper Contributor)

Actually, with this scenario, that seems to be recommended officially - Using a third-party cloud service with Office 365


"I plan to have Office 365 host all of my organization’s mailboxes. My organization uses (or plans to use) a third-party (mail services) cloud solution for filtering spam and malware. All email sent from the Internet must be filtered by this third-party cloud service."


You point your MX record to your third-party service provider.  I don't think Exchange Online Protection can be turned off completely but for example, you can set a mail flow rule to bypass email from spam checking originating from the third party service. I think the documentation could be clear on the whole!


I'd get advice from your 3rd party provider and they should be able to recommend the best practice for their particular solution and Office 365 integration.