Enable Greylisting fails

Clicked on "Try Greylisting"

Virtualmin responded that Postgrey was not installed and offered an install button

Clicked that. yum attempted to install but the install failed

When I went back to the greylisting page, it says "Greylisting is not currently fully enabled on your system. Click this button to have Virtualmin configure it"
When I click that button I get this:

Enabling Postgrey at boot time ..
socket failed : Address family not supported by protocol
Call Stack Trace
File Line Function
/usr/libexec/webmin/virtual-server/postgrey-lib.pl 263 WebminCore::error
/usr/libexec/webmin/virtual-server/postgrey-lib.pl 148 virtual_server::allocate_random_port
/usr/libexec/webmin/virtual-server/enable_postgrey.cgi 11 virtual_server::enable_postgrey
(eval 45) 6 (eval)
/usr/libexec/webmin/miniserv.pl 2133 (eval)
/usr/libexec/webmin/miniserv.pl 752 miniserv::handle_request
<-

What should I do?

Status: 
Closed (fixed)