Wayland compositors have one great feature (at least for me), they perform screen scale independently on actual hardware. So I can set 200% desktop scale on semi HiDPI monitor (4K & 28″) and all Wayland applications work immediately at that scale without font adjustments/various DPI tweaks/etc.
So here comes the Thunderbird with Wayland backend. I generally did the package for my personal needs and you can have it too 🙂 Just get it from Fedora repos as
dnf install thunderbird-wayland
You’ll receive ‘Thunderbird on Wayland’ application entry which can be registered as default Mail at
Settings -> Details -> Default Applications
Some background info: recent stable Thunderbird (thunderbird-60.5.0) is based on Firefox ESR60 line and I backported related parts from latest stable Firefox 65. Some code couldn’t be ported and there are still issues with Wayland backend (misplaced menus on multi-monitor setup for instances) so use the bird on your own risk.