Forum Discussion

Copper Contributor

Feb 22, 2021

Problem with mail delivering via SSL error 454 4.7.4

Hi we have problem with delivering mail from fortimail appliance to exchange 2016 infrastructure, sometimes emails stuck at fortimail and not delivered to exchange with this message: dsn=4.0.0, ...

2016

Exchange Server

MDadarkar

Copper Contributor

Feb 23, 2021

Jozi Zurbej

Hi,

The issue can be caused by one of the following reasons:

The Exchange server is experiencing Time synchronization issues.
There is a replication issue between the domain controllers.
The Exchange server is experiencing Service Principal Name (SPN) issues.
The required TCP/UDP ports for the Kerberos protocol are blocked by the firewall.

https://docs.microsoft.com/en-us/exchange/troubleshoot/client-connectivity/454-4-7-0-temporary-authentication-failure

https://www.thecloudtechnologist.com/how-to-fix-exchange-online-hybrid-outbound-connector-454-4-7-5-certificate-validation-failure/

Regards,