For the most part, our email works great. However we are getting some failed emails to some (two) outside organizations. The error in the Exchange Queue Viewer is Error: 450 4.7.1 Client host rejected: cannot find your hostname, [IPADDRESS]. The issue I see is the IP address it lists is the ip address we use to browse the internet, not the SMTP address. There are reverse DNS and pointer records for both our primary and secondary MX records.