This error occurs when TLS authentication fails for the SMTP server. It can be caused by the server security certificate being incompatible with the TaskCentre software.
⚠️ **Important:** TaskCentre versions prior to 4.7 cannot use TLS at all, and versions prior to BPA 2020 Update 1 cannot use TLS 1.2. Versions prior to 4.8 (BPA 2018) must be upgraded to BPA 2018 first, before upgrading to BPA 2020 Update 1 or later.
The recommended fix is to upgrade to the latest version of TaskCentre. Alternatively, you can disable secure SMTP as a workaround — this only works if your SMTP server allows anonymous relay from the server hosting TaskCentre, and will reduce security. Follow these steps to disable secure SMTP:
Log in to TaskCentre.
Click **Manage**, then click **Tools**, then click **Output**.
Click Send Message (SMTP).
On the **Advanced** tab, clear the **Use Secure SMTP** checkbox.
Click OK.
Another possible cause is using the server IP address instead of the server name in the SMTP settings. Ensure the fully qualified domain name is used in the **Server Address** field on the **Main** tab (for example, w2k3-exchange.mycompany.net).