If the spam notice is coming from Roadrunner, there is something that sets off the spam notice, words in the text, the source of the email (the email provider, in your case RoadRunner). Your last post indicating that it does not always happen, shows that there is some common element in all the questioned mail. If you look at them carefully you may be able to detect the cause. If you get email on a regular basis that is being marked, put that address in your address book and that will stop it.
If you stop a few because of the source, once you accept that source several times, the problem should stop. We have to wait and see.