That only applies to imap mailboxes where Zammad is supposed to keep the messages on the server (not default setting)
Sorry I’m confused.
You’re saying you can reach office 365 services via Zammad without issues but some asian mail provider is not reachable?
To be honest, this sounds like a specific issue and is probably out of Zammads scope.
Ensure you can reach said mail servers from Zammad servers console. Ensure the ports are accessible from that machine. If they’re not, don’t bother trying within Zammad because that won’t change the result.