Forum Discussion
Is there something wrong with M365 spam filtering?
Hi All,
I work for a small MSP and have received multiple reports of legitimate mail being flagged as spam by 365 and sent to the recipient's Outlook Junkbox, seemingly at random.
It's happening to too many clients in such a short space of time to be anything other than a service issue but there's no mention of it anywhere.
Is anyone else noticing anything similar?
Hello ljblackhall
The Exchange Online Protection (EOP) scanning mechanism is subject to so many factors, when categorizing an inbound email, which includes the reputation of the sender's domain and IP. The reputation of a domain or IP changes overtime depending on how it is being used to send emails over the internet. You could check the IP and domain reputations of an email with the tool below:
If the email was received into the user's junk folder, then the user should report the email as not spam so the EOP engine improves on its classification techniques, for subsequent emails from the reported sender(s). The user may, also, add the sender's email to their trusted sender's list, especially, if the reputation remains bad.
As an administrator, if you have the subscription that includes Microsoft 365 Defender for Office 365 plan 2, you should check for the delivery action of the reported email in the Threat Explorer of your Security portal.
Also, you should align your security configuration with best practices as described in the useful article.
In addition, it is important to note that the preset security policies (standard or strict), if turned on takes precedence over the custom policies.
Useful Articles
Please do not hesitate to contact me with useful questions you might have on this issue.
Thank you.
ljblackhall I've been seeing the same thing - valid incoming mail from outlook hosted domains being sent to junk, and recipients of our mail saying they cannot find our messages. I tried opening a ticket with MS but got nowhere, just the same recommendation to ask people to mark our mail as not junk, which we have done but no indication of what's really going on. Definitely something up in the system.
You may check further by using MX tool:
https://mxtoolbox.com/EmailHeaders.aspx
Before this, please also make sure:
1. Make sure you mark the messages as not junk
2. Add the sender to your safe senders list
3. Add the domain to the safe domain list
- Definitely. They are doing it wrong. Customers I email all the time wind up in Junk often the past few weeks. My instincts say it's all the changes their making to prepare for new Outlook.
It's not just you.
