Emails to Microsoft365 accounts marked as Spam or blocked

Copper Contributor
Hello,

My company uses Google workspace however we recently began having an issue when sending emails specifically to external domains that use Microsoft365 email servers. 
 
I found that there were problematic links in our "automatic Footer". A test I ran showed that emails with the Footer were marked as Spam, whereas emails without the Footer went to the Inbox. 

However, even after removing the Footer, this behavior is not consistent. We still occasionally see some emails (without the Footer, and without any hyperlinks) being marked as Spam/Phishing. Specifically the email headers contained this:
* `CAT:PHISH`
* `SCL:5`
* `SFTY:9.25`
in the `X-Forefront-Antispam-Report`.

DKIM and SPF authentication was successful for this same email.
 
Additionally some emails never arrive at all, not even to the spam folder, no Quarantine email. Therefore it's impossible to inspect the headers of these emails. 
 
What are the suggested troubleshooting steps to fix this issue? How do we understand WHY Microsoft considers our emails as "Spam" or "Phishing" ?

Thank you

 

 

1 Reply

@driangle-mimi 

 

How about your Email Domain and sender IP?