After much struggle with all clients known to me, I now use Thunderbird.
I might not keep using it for a longer time, so I kept the old
configuration and disabled it, so it can be reused at a later time.
Because Thunderbird doesn’t support nice declarative configuration, I
don’t see much sense in configuring the accounts declaratively, when the
settings for the accounts (which is much more) have to be configured
manually.
This is needed for Intel Arc support (Mesa 22.3+).
This also makes changes so the nixpkgs system evaluates without
errors/warnings (caused by my configuration).
This does not use the home-manager provided account module, because it
does not support notmuch, LOGIN authentication and special characters in
user names.