Originally it was london.mxroute.com:2096, but now is is https://london.mxroute.com/roundcube, it seems. Which does not work for CNAME.
Is there a way to have custom CNAME, since adding CNAME for london.mxroute.com or webmail.mxroute.com both yield an “Apache is functioning normally” message page.
The same settings that worked before the DA transition work after, and fortunately those carried over well. The DA-specific tutorial though is here:
https://mxroutehelp.com/index.php/2019/08/25/custom-webmail-pop-imap-smtp-domain/
Great. Thanks for that link, as I had no luck in finding that guide on my own, unfortunately. My search-foo might be off…