sendmail configuration file
/etc/sendmail.cf
The sendmail.cf configuration file contains the information needed to route mail between local and remote systems.
To customize your sendmail configuration, we strongly encourage you to get a copy of Sendmail by Bryan Costales, O'Reilly & Associates (ISBN 1-56592-056-2). This book is often referred to as ``the Bat book'' because of the picture on its cover.