451 4.7.0 Temporary server error. Please try again later. PRX2

Another day of troubleshooting with a student from Learn Exchange from beginner to master. A straight configuration of Exchange Server 2019 has completed successfully, but testing email reception were not successful.

I asked my student to manually emulate email SMTP communication, which ended up with the title error of this blog.

It points to a DNS resolution error. So I asked to check the network card bound for the internal DNS lookup can resolve the exchange server's DNS name.

A Quick fix to this issue is to add DNS entry to the local Host file.

C:\Windows\System32\drivers\etc\hosts.

192.168.16.1 server

192.168.16.1 server.domain.com