Are you the end user or sysadmin of smartermail?

The most common cause of this type of error is having the SSL/TLS settings, port number, or hostname settings incorrect. It's also possible your computer doesn't support the right versions of TLS and may be rejecting connectivity because of that. Do other email clients fail with the same settings?

In Outlook, you need to check the box for "my outgoing server requires authentication", with the sub-option to "use the same credentials as for incoming".  This is my most common mistake.

Ports:   If you use SSL/TLS encryption option in Outlook, the matching SmarterMail port needs to be configured for "SSL", which means mandatory encryption.   This is best.  

If you use the STARTTLS option in Outlook, the matching SmarterMail port needs to be configured for "TLS", which means optional encryption.

Thank you everyone for your answer and support,  I still can't add the account to outlook, my windows server is fully updated, Smartermail is well configured, i have the same configuration for all users and the problem only occurs with email users who use OS Windows Outlook, all OS Macos Outlook users work without problem. 

In Windows, I updated the Framework to version 4.8 and reviewed the firewall configuration. I also tried to configure different versions of Outlook and I still have not been able to configure the email for Windows users. I dont know what more do.