Permalinks with a dot?

I am re-desining a website into wordpress that needs to contain the same URL’s for SEO reasons

No they don’t. The old URLs need to redirect to the new locations, but you don’t HAVE to keep .html in there. 301 .htaccess redirects can do this.

As for how to make WP show .html at the end, edit the permalinks to end with .html

So you’re saying it’s more efficient to redirect the old URL’s? What might I use to do this?

This company has spent the last 10 years link building, so it’s very important to them for this to be accurate.

Thanks!

Efficient … hard to say. Depends on what URLs your starting with. Better in the long run? I think so, since it means once you’ve gotten them redirected, you don’t have to worry about it and can go forward with modern URLs.

https://en.wikipedia.org/wiki/URL_redirection
https://corz.org/serv/tricks/htaccess2.php
https://www.htaccessredirect.net/

Basically you make a 301 redirect in .htaccess. You can even make the URLs ‘the same’ – like if you have today domain.com/about.html, make a page called ‘about’, make sure it has that as it’s SLUG (that which is translating your dots to dashes right now) and then just toss this in your .htaccess:

RedirectMatch 301 (.*)\.html$ https://www.example.com$1

That will send all whatever.html to just plain ‘whatever’ and you’re done.

The setup is a pain, but once you’ve got it down, you’re done.