Topic: SMTP AUTH is required for users under this sender domain
==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.3.2 MARIADB edition.
- Deployed with iRedMail Easy or the downloadable installer? Downloadable Installer
- Linux/BSD distribution name and version: Debian 10
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
We experiencing a problem from time to time, when someone send email from account in our domain in o365 to account hosted on iredmail.
o365 have permission to talk behalf of our domain - CHECK_SPF_IF_LOGIN_MISMATCH is enabled and SPF record contains include:spf.protection.outlook.com.
Thousand or more emails per day from o365 in this scenario are sended properly, but some are not (<10). How to resolve this issue, where to search problem - dns, iredapd related settings or maybe something else?
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