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, stat=Deferred: 454 4.7.4 temporarily failed to deliver message via SSL/TLS.(Reason:454 4.7.4 temporarily failed to deliver message via SSL/TLS.)
this errors ocasionally occurs and emails are going to timeout and not delivered after few days,
I cannot find nothing about this error code, and to troubleshoot.