Summary:
I'm receiving the warning message: Hostname does not resolve in DNS. What is this and how can I fix it?

The hostname for your PerfectMail server is the "outside" facing hostname, that is the hostname that an external mail server would see when connecting to your PerfectMail server.

In SMTP exchanges the hostname is important for both identification and validation; it should resolve on external DNS servers (i.e. it should have an 'A' record.).

If your hostname is resolving locally and you are still receiving this warning you should try performing DNS resolution from an external site, or directly querying external DNS servers. It is very probable that your DNS changes have not propagated to the outside world.

PerfectMail has a Validation script that runs every 15 minutes looking for potential issues, which it will reports on the web interface. After resolving your DNS/hostname issue the validation script will automatically clear any errors or warnings. You can initiate the validation script manually on the PerfectMail Dashboard screen.