==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):
- Deployed with iRedMail Easy or the downloadable installer?
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hello,

No e-mails are received from Yandex mail users to any e-mail accounts on iredmail. The following error is returned to the account that sent the email.

Recipient address rejected: SMTP AUTH is
    required for users under this sender domain (in reply to RCPT TO command)