Our 365 Emails to other 365 tenants going to junk

Copper Contributor



We are currently a month into diagnosing an issue with other 365 tenants marking our email as spam, we've reviewed headers, DKIM, DMARC, MX SPF, every little thing we can think of and still getting marked as spam.


Adding more to this, it's consistently inconsistent, even the engineers at Microsoft are puzzled, we spent about $2000 on an exchange engineer, everything is perfect, his testing was flawless, BUT still face these issues with many companies.


What's next? I am at a loss.

3 Replies

I feel you. Had the same issue with one customer. Headers showed no problems. Implemented SPF -all and DMARC p=reject but still, emails went was marked as spam at recipient.

In this case it turns out that the sending domain website (in this case it was WordPress but it can happen to any website) was infected with malware which probably caused their domain to be marked as suspicious. However, it was very hard to find this was the cause. On reason could also be that everyone linked to the website in their signatures.

Going to run some scans tonight, that would be amazing.

@TimSANConceptsi have the same issue. Found a solution?