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.