Postix Ubuntu only sending to gmail.

So I’m currently working on my website where I set up postfix with Wordpress registration emails. Now while users can receive emails at gmail.com. Yahoo, Hotmail etc. are not able to receive emails, now I’ve googled and googled with no luck - I found another thread here about it, but that problem was solved with a new droplet. I’ve tried with a new droplet (new ip.)

And checked if my ip / domain was blacklisted with mxtoolbox.com, which is not the case. Have also opened ports that was needed, even tried disabling my firewall.

So please any help, is great at this point.