I get a lot of emails from OGR because I follow a lot of topics. Often, I'll get a half-dozen or more on the same topic, so I'll open one and then click on the topic rather than opening all of the other emails. Thus, a lot of emails from OGR go unread, so Outlook sometimes thinks that I'm no longer interested and starts sending them to the junk file. I've mostly fixed this by marking a lot of the emails as "read". Outlook still randomly treats some as junk.
Remember that the computer is smarter than you are and knows what is best for you.