[Plugin: Custom Contact Forms] Connecting to SMTP host

I’m trying to create a form that can be emailed to my client. I’ve tried SMTP info from two different email servers (Godaddy and Yahoo) and both of them get an error message on the page that says SMTP Error: Could not connect to SMTP host.

Any ideas what I could be doing wrong? I’ve tripled checked everything to make sure I’m typing it in correctly.