==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.8
- Deployed with iRedMail Easy or the downloadable installer? Installer
- Linux/BSD distribution name and version:  Ubuntu 22.04 LTS
- 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.
====

These errors were shown up last 3 days ago, not before.
postfix/smtpd[2106755]: warning: TLS library problem: error:0A000415:SSL routines::sslv3 alert certificate expired:../ssl/record/rec_layer_s3.c:1584:SSL alert number 45:

This is really weird for me. The certificates surely still valid and active.
I use Let's Encrypt SSL certificates. I can visit the website and it's not complain about the certificates.
But from the log above, there are almost hundreds log with same error message, mention about expired certificate which is not true. But how SMTPD mention it. So now, I can received connection from out world. They are all break the connection due the error.

I read about the ECDSA and RSA certificates from Let's Encrypt, however I setup from beginning using ECDSA and no problem. It just shown since 3 days ago.

Anyone experience the same problem?