[{LED=450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)} Exchange 2016

Question

Outbound ,ail flow issue in exchange server 2016.

Certain emails emails with size of 100 kb or large and with attachments get queued in exchange due to this notorious error [{LED=450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)}

My send connector is health and can send emails to certain domain without issues.
The default send connector inactiveconnectiontimeout and messagesize settings is fine.

My firewall does not show messages being dropped or denied.

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The temporary solution that have used to get rid of this is:

Create a separate connector**(only set require TLS)** for that specific domain whose recipient mails is being queued, then restart transport service. But is not the right way to handle it because its unhealth to keep on restarting the transport service since it impacts the entire exchange organization.

I just need a permanent solution to this.