Hmm ... just to asure I'm not getting things wrong:
You wrote, you're connecting to smtp.XXXX.net, but actually you're connecting to a different server?

My mail server is not the issue xxxx is short for my real domain server. Sorry I send mail with other websites to that address just fine. OSSN tells me that I authenticated, but when I try to send mail, nothing happens.

As I wrote already in my first comment: your ISP xxxx.net resolves to localhost (127.0.0.1)

This IP is the default address used by every server worldwide for INNER TCP/IP connections, but not for outgoing traffic. Why? Because it is not backward resolvable. And that makes sense, because otherwise a mail reply to 127.0.0.1 would reach EVERY server worldwide. No good idea.

So either ask your provider to set up his DNS records correctly using a resolvable address, or use a different SMTP server.

I do not have my own smtp server. I am authenticating through my ISP.

Yes, because you have no mail server (as you already wrote).

smtp.XXXX.net resolves, but when I try and email, nothing happens.

smtp.XXXX.net resolves to localhost, but you wrote I do NOT have an own SMTP server !?!