What does that mean: LOCALHOSTRELAY Alert

After sending my first newsletter, I got these warning emails from the server and I don't know what this mean, if I should worry about it or not.

is a salvage title bad

I sent 7,646 emails, a thousand email per hour and it has just finished. It looks like it went well with only 16 bounces.
The server setup is not performed correctly. That is why you're getting this alert.

It's NOT related to your mailwizz install