Is it possible your browser might be replacing the password you're putting in with a saved password? Just as a test, try logging in to SmarterMail from a guest/incognito session and update the certificate password one more time. I have seen the browser auto-fill attempt to update passwords here even though these fields are marked as not to be auto-filled!

Kyle, when i select the .pfx file in bindings for use and enter the password it's all fine. I've tried entering an incorrect password and it definitely doesn't let me save it. So it's definitely the correct password being saved (in bindings).

But when I go to the SSL Certificates area it shows the certificate cannot be loaded with password provided.

Is this because the .pfx files were added manually to the certificates folder from the web server using RDC as a pose to uploading the .pfx files via SM?

That's the only difference I can think of.

The one that is showing as active was one I uploaded using SM.

Actually, if I upload a certificate via SM and then try and use it in the binding area it says that it is "Not a Valid Certificate" (even though it's uploaded and says it can be used), Why is this?