There are various URLs exposed in various emails from the list, many of which are wrong.
The underlying issue is there are generic replacements such as $listinfo_uri and $user_options_uri in various templates such as the welcome.txt list welcome message and the footer-generic.txt message and digest footer. Now that the Mailman 3 core engine has been separated from the web UI, the core doesn't know what these replacements should be and there is not yet an interface to get them from Postorius or whatever the web UI is.
In the mean time, I have made list specific versions of welcome.txt (done before announcing the list) and footer-generic.txt (just now) with the correct URLs hard coded.
The purpose of this post is two-fold. To explain the issue, and to test the footer.
There are probably more of these incorrect replacements and I will fix them as I notice them or they are pointed out to me. Note that I am aware that the https URLs in the List-Subscribe: and List-Unsubscribe: headers added to posts are wrong, but I haven't got a handle on this yet. The mailto: links in those headers are correct as are the Archived-At: and List-Archive: URLs as there is an interface to get those from the archiver.