Hey, everyone! Our email troubleshooting documentation is here:
https://docs.ninjaforms.com/customer/en/portal/articles/2045713-troubleshooting-ninja-forms#ts_email
It’s important to note that Ninja Forms is actually not responsible for sending the emails. We pass the data onto your local WordPress -> PHP installation, which is usually managed by your web host (unless you are using an SMTP plugin, or you are self-hosted). Every host has their own policies and procedures for sending emails from their servers that may need to be addressed.