I need help to configure a private domain name with Thunderbird

I suggest contacting the organization that created it to get the appropriate server settngs for the domain. If you did this through a web hosting company, that information is usually available in their cpanel webpage.

I am the organisation that set up the domain, I have access to the DNS server but cannot find anywhere in Tbird the codes I need to set this up...

So I am assuming it is not possible to set up Tbird to import mail from a domain name server?

What I am saying is that a domain name server is not generally sufficient as an incoming mail server and an outgoing SMTP server. Is this where you created the domain? https://www.argeweb.nl/ My concern for you is that, if you set up the domain from a web hosting company, you need to contact them for the proper email server settings.

As a further comment, if you used their webhosting feature, there will be a cpanel service available that should have the info for setting up an email account and will also give you the settings for using an email client.

I've had syrett.nl with argeweb for 14 years and never had a problem. I have always downloaded/transferred my email first to Google and later to Microsoft, and if there were ever problems this is where they always occurred. Thanks for your feedback, but I am going to leave things as they are here and find another route

Are you thinking that Thunderbird should operate like an e-mail service after you point MX (and DNS?) records to it? It is not that kind of product/service.