The official Release Notes for Sendmail 8.14.5 are available here - http://www.sendmail.com/sm/open_source/download/8.14.5/?show_rs=true#RS
To upgrade the application, go to the Control Panel > Applications > (scroll to the bottom of the screen) Update System. In the System Update screen > States to display (the first listing), click on Installed. The system will have to load over 350 packages, so please be patient.
Once all the packages have been loaded, scroll down and search for the three sendmail packages: sendmail, sendmail-cf, and sendmail-doc. If you have installed the CentOS 5 Development Tools, you will have a fourth sendmail package: sendmail-devel. Click the check boxes to the left of all the sendmail applications, and then scroll to the bottom of the screen and click Update Selected Packages.
In the next screen, click Install Now to install the updates. Once the updates are installed, the applications will show the new version in the Installed screen.
