==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.7.4
- Deployed with iRedMail Easy or the downloadable installer?downloadable installer
- Linux/BSD distribution name and version: Ubuntu 24.04.3
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Web server (Apache or Nginx):Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes, iRedMail Pro 5.8 LDAP
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hi, actually we did migrate our old iredmail server to the new server due we did enhance the new server with large storage and upgarde for the server specification. We did follow the guide on how to migrate from old server to new server..from old server the latest version is up tod ate also beore we do the migration. Everything is smooth..vmail data/user data..since almost 2 weeks running without issue, now we did notice based on end user report which
-on New Outlook incoming mail seem ok..able instant receive/sync the email-
-compare to Classic Outlook, email seem delay sync with server
-for those using Outlook Apps on phone, sometimes ask for sign in although auth is correct and sync will be take so long on this outlook apps

we did check, this due the issue on smtp_tls protocol which if we set to min 1.2, on Outlook Apps & New Outlook will be issue to sign in. Thus we reduce to min 1.1, the auth on this New Outlook and Outlook Apps no issue on sign in..but its effected Classic Outlok and Apps Outlook on get delay sync from server.

on dovecot.conf file set to this  ssl_min_protocol = TLSv1.1

Need support and advices.