You need to authenticate, otherwise your SMTP server doesn't know it is you from Adam and will refuse connection.
Port 993 and SSL should be used for IMAP (incoming) and port 465 and SSL for SMTP.
I think the mistake I made was ticking the Secure password authentication box.
Have got it working without changing any of the default settings, besides going to More Settings/Outgoing server and selecting use same settings as my incoming mail server. A simple solution.
But in the meantime I have changed my ISP to Plusnet. hen I should be changing my hosting company. Thanks for your assistance and more your patience as I stumbled my way through this.
Glad we got there in the end.