You can send emails from Clearpass with gmail. Here is a good explanation.
If you want to use hotmail to send emails from Clearpass, below is a little procedure:
Setup the server in Clearpass messaging:

As Digicert is used to sign the certificate of the smtp.live.com, we have to add it to the trusted certificates:

Add Digicert Global Root CA to trusted certificates

If the correct certificate is not trusted, the following error in event log: 
Also, the 'Default From Address' has to be right ...

... or the following error will show up in the event log:

Test and good to go :)

