Our 365 Emails to other 365 tenants going to junk
Team, 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.