sendmailcf
sendmail.cf is the runtime configuration file used by the Sendmail Mail Transfer Agent (MTA). It governs mail processing, routing, and delivery decisions and encodes policies for domains, hosts, and users. The file is read by the sendmail daemon when it starts or reloads, and errors in its syntax can prevent mail from being delivered.
In most modern deployments, sendmail.cf is not edited directly. Administrators modify a higher-level file named sendmail.mc
Location and structure: sendmail.cf is typically found at /etc/mail/sendmail.cf or /etc/sendmail.cf, depending on the operating system.
Maintenance and usage: applying changes requires reloading or restarting the Sendmail service so that the new