Install sendmail alternative on RedHat

manifests/service.pp

@@ -11,4 +11,11 @@ class postfix::service {
     hasstatus => true,
     restart   => $::postfix::params::restart_cmd,
   }
+  if $::osfamily == 'RedHat' {
+    exec { 'alternatives --set mta /usr/sbin/sendmail.postfix':
+      require => Service['postfix'],
+      path    => '/bin:/sbin:/usr/bin:/usr/sbin',
+      unless  => 'test /etc/alternatives/mta -ef /usr/sbin/sendmail.postfix',
+    }
+  }
 }