Contact Form Redux will display a colored border around error messages when you attempt to send an email using a contact form and the operation fails. The colors used for the border of the error messages can be used to help troubleshoot the cause of the error.
The green border is used when an email is successfully sent by Contact Form Redux.
If the message doesn’t reach its intended recipient, the email was most likely blocked or intercepted prior to delivery by your mail server or the destination server.
You’ll see an orange border on a contact form error message when one of Contact Form Redux’s spam prevention features has blocked the email submission.
A red-bordered message means that Contact Form Redux tried to send the email but was unable to do so due to a server or configuration issue.
It could mean your server’s mail system is down. Troubleshooting red-bordered error messages begins with verifying that your mail server is functional and not having issues.
By default, Contact Form Redux uses WordPress’ wp_mail() function, but it’s also possible to use SMTP.