If your website is not sending emails, whether it is WordPress, a contact form, or some other software you have, we have SMTP (email sending) restrictions in place. Email cannot be sent without SMTP authentication. We strongly encourage you to use TLS/SSL authentication in order to protect your password.
Due to abuse, all email being sent from your account is required to be authenticated. No exceptions to this policy.
Please contact your software vendor for how to send email using authenticated SMTP or check the software documentation.