Okay, so I decided to implement autoconfig / automail. I have two domains I will call them, client.com and mailserver.com I have an A record created for autoconfig.mailserver.com propogated and working, I can test for config settings for that domain and any other mail domain within ISPConfig that uses that mail server. The trouble I am having is setting up the CNAME for the client.com domain. When adding the CNAME i entered: NAME: autoconfig.client.com. DATA: autoconfig.mailserver.com. DNS propogated, ive done a CNAME check: autoconfig.client.com returns autoconfig.mailserver.com So, why can thunderbird get the settings when i use [email protected] but not [email protected] Have I misconfigured the CNAME? Code: ;; ANSWER SECTION: autoconfig.client.com. 0 IN CNAME autoconfig.mailserver.com.