I am new to ISPConfig, but not new to server management. I'm having an issue that is confusing me. I migrated to a new server running ISPConfig 3 and set the server up according to the Perfect Server instructions, etc. All web sites I've moved to the server are behaving properly. However, I'm having issues with some email being marked as spam. I currently have all domains on a single IP address, and all of those domains use GoDaddy as their nameservers. Each domain record is correctly formatted with SPF, DKIM and DMARC records. They all have correct MX Records too. However, a client was hearing that his email was being marked as Spam after switching servers and this was not happening prior to the switch. Testing confirmed this and also that some email was not being delivered at all. Likely, this is due to being filtered out by an even more stringent spam filter. The only thing I can see that could possible cause this is that the MX records do not have matching IP addresses when attempting a rDNS lookup. I can't configure a rDNS entry with GoDaddy, and I don't use their Mail Servers. My machine has a single IP address and I have not configured my own nameservers. So, since I have many domains using the one machine IP address, does anyone have any idea how I might resolve this issue? Thanks in advance!!!