These errors occur when authentication fails for the SMTP server when the TLS protocol is in use. This can be caused by the server security certificate being incompatible with the TaskCentre software.
TaskCentre versions prior to 4.7 cannot use the TLS security protocol at all and versions prior to BPA 2020 Update 1 cannot use the TLS 1.2 security protocol.
The resolution would be to upgrade to the latest version of TaskCentre. Please note that versions prior to 4.8 (BPA 2018) must be stepped to this version first, before then upgrading to BPA 2020 Update 1 or later.
A workaround is to disable the use of secure SMTP by TaskCentre. This will only work if your SMTP server is configured to allow anonymous relay from the server hosting the TaskCentre software and will of course be less secure, so please be aware of this before disabling it.
To disable the use of secure SMTP in TaskCentre:
Log in to TaskCentre.
Click Manage, Tools, Output.
Click Send Message (SMTP).
On the Advanced tab, clear the Use Secure SMTP check box.
Click OK.
Another cause of this issue may be the use of the server IP address instead of the server name in the SMTP settings.
Ensure that the fully qualified domain name of the server is used in the Server Address field on the Main tab of the SMTP settings. (For example, w2k3-exchange.mycompany.net).