Unfortunately, I just left on a business trip, so I won't be able to check my settings for a while.
Also, I'm running Avast on my desktop. I had my SMTP set to use TLS if possible. I got an alert from Avast saying that I shouldn't use encryption as then Avast couldn't scan the emails, and that Avast would encrypt the traffic. So I turned it off. I haven't verified that Avast is encrypting the traffic, but Untangle is able to see the outgoing SMTP messages.