I had the same problem, and I just finished solving it! I needed to an SMTP service, and installed the WP Mail SMTP plugin. In their set up, they give you options (SendLayer, Mailgun, Mailjet, Sendgrid, etc). Instead of another external service, I contacted my webhost provider – SiteGround – and they helped me set up my SMTP record and events through them. It’s included with my web hosting fees. I don’t know what provider you use, but they might help you set up SMTP.
I hope this helps 🙂