Popular email clients like Gmail, Yahoo, Outlook, etc are constantly improving their services to reduce email spam. One of the things their spam tools look for is whether an email is originating from the location it claims to be originating from. If the proper authentication isn’t there, then the emails either go in your SPAM folder or worst not get delivered at all.
This is a problem for a lot of WordPress sites because by default, WordPress uses the PHP mail function to send emails generated by WordPress or any contact form plugin like WPForms. The issue is that most WordPress hosting companies don’t have their servers properly configured for sending PHP emails. The combination of two causes your WordPress emails to not get delivered.
To avoid that use WP Mail SMTP by WPForms plugin: