Bill, use Mail Enable plug-in mail test and see what error message comes up.
https://moodle.org/plugins/view.php?id=1527
I am assuming you haven't configured SMTP on your server, as since IIS 7, Microsoft wanted people to use their proper mail servers like Microsoft Exchange so stopped supporting built-in SMTP in IIS 7 and onwards, but this doesn't mean you wont be able to set it up.
There are two options, one is setting up third party mail system www.mailenable.com they offer a free version to set your email on a windows server, apart you can use features and roles and install SMTP server, that will additionally install IIS 6 interface to let you setup basic mail system.