Topic: email sent to MS365 goes into Junk Mail
==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.4.0 MARIADB edition
- Deployed with iRedMail Easy or the downloadable installer? installer
- Linux/BSD distribution name and version: Ubuntu server 20.4
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):Nginx
- Manage mail accounts with iRedAdmin-Pro? no
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
So I have a strange problem.
I have Iredmail set up and working perfectly. I have correctly configured DNS records – MX, SPF, DKIM and DMARC are all good. If I send a test email to https://www.mail-tester.com I get a 10/10. I can send emails to Gmail no problem. My public IP does not have any reputation issues and is not on any blacklists.
But – If I send emails to any user on Microsoft 365, they almost always end up in the Junk Mail folder. I have looked at the headers and according to MS, they have a Spam Confidence Level or either 5 or 6, but there is nothing to explain WHY they have an SCL this high. This is a big problem from me as many of my users will want to send emails to MS 365 addresses. Can anyone suggest a solution?
Thanks in advance.