NGINX Configuration Structure
Zimbra NGINX POP/IMAP has a hierarchical configuration structure. Top level configuration files include other functionality-specific configuration files. The main configuration file is /opt/zimbra/conf/nginx.conf, and this includes other configuration files as per the hierarchy below
/opt/zimbra/conf/nginx.conf
This is the main top-level NGINX configuration file. It defines the working directory for NGINX worker processes (/opt/zimbra), and includes the main, memcache, mail, and web configuration files