To me there’s a certain…aura(?) I suppose you could say around messages/feelinge/communications from the dead. I’m not sure how to describe it, but it’s pretty easy for me to determine now. I first started to notice it with photos. I would get a different feeling from a person that was dead in a photo vs one that was alive. I had an issue when I was younger of knowing/trusting myself on if what I was picking up was from life or death unless obvious and once I got into collecting old photos it helped me to train my sense of that “aura”.
Not saying you have to go collect old photos, but maybe look at r/mediumreadings where there are photos you could use…or maybe if you have old family photos…somewhere where you can see if you can determine the person who has passed before knowing the information. Keep doing this and you’ll start to understand that feeling.
This is just one of many ways. It’s worked well for me, maybe it will help you or someone else on this thread!