oh, we're up here now?
The reason it's work, for pop at least using IP is because you've got some sort of dns issue going on
Your not actually running a mail server are you i.e you have you're own domain name and email get's send directly to you on your computer, but rather the Juno thing is just another email account provided by Juno or something like that, if it is it'd be a bit harsh for your isp to block you accessing another mail server other than their own (which I'm guessing here cos I don't know who or what Juno is being in the UK)
The smtp IP address may be wrong, best people to ask would be your ISP
Check aswell your email account settings in evolution for the account check the server type says SMTP and not sendmail or anything like that, unless that's what you're trying to used.
Apologies if this sounds a bit of a muddle but it can be quite easy to get into one trying to help on a forum