[root@piper ~]# yum install postfix
Setting up Install Process
Setting up repositories
update                    100% |=========================|  951 B    00:00
base                      100% |=========================| 1.1 kB    00:00
addons                    100% |=========================|  951 B    00:00
extras                    100% |=========================| 1.1 kB    00:00
Reading repository metadata in from local files
Parsing package install arguments
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for postfix to pack into transaction set.
postfix-2.1.5-4.2.RHEL4.i 100% |=========================|  39 kB    00:01
---> Package postfix.i386 2:2.1.5-4.2.RHEL4 set to be updated
--> Running transaction check
--> Processing Dependency: /usr/sbin/alternatives for package: postfix
--> Finished Dependency Resolution
Error: Missing Dependency: /usr/sbin/alternatives is needed by package postfix
[root@piper ~]# ll /usr/sbin/al
alsactl       alternatives