Hello Christian,
If you hadn't cross posted, the likelihood of your finding out that you made a typographical error in the blinx list would be more obvious.
I've eliminated that in my reply.
One remaining client which I actually prefer which is sadly NOT supported by Debian is SEAMONKEY.
Have you tried that? Developers have a history of ignoring the correct sensibilities of the users, so I don't see them changing anything even though you're right, we are losing an excellent email client.
Here's how to install SEAMONKEY, I wish it was an official package, because it provides a wonderful html editor.
Neither method they give is without problems because of possible library conflicts with Debian, although I've added the repository which contains Thunderbird, and also Firefox which can conflict with what Debian packages and might start a "free" - "non-free" fight about artwork which I think is so silly because it and multimedia keep Debian from being the premier Linux Distribution it could be if "only" it had normal and useful applications that did something the user needs without much user customization of sources like using the Swiss Source Generator to include "forbidden" programs:
https://debgen.simplylinux.ch/
So sad to lose Thunderbird, it's back to mutt with w3m as a html viewer for me.
Best wishes,
David
Best wishes,
David