When sending emails through Kennel Connection, this is the process:
When you hit send or it's time to send automatic emails, KC logs into your email provider's server. Once your login information is authenticated, KC sends all emails to your provider at once. That is all it does. Your provider will then send the emails to your client.
This error means that you have the TLS security option selected but are using port 25. Port 25 is an unsecured port and cannot be used with TLS security.
You will need to find out which port your email provider wants you to use. You can search online or contact that company. This error is not coming from KC so there is nothing you can do in KC other than assure you are using the correct settings in File, Business Info, Email tab. If you are but continue to get the error, contact your email provider for further assistance. Let them know you are trying to get your email account setup in a third party software and provide them with the error message.