Thunderbird / K-9 Mail 20.0

New:

Enable easily discoverable way to configure and use Thundermail (#11086)

Changed:

Only show message notification configuration actions above the cutoff (#10301)

Fixed:

Account drawer stayed open after account switch despite auto-select Inbox setting (#10120)
Imported settings could incorrectly show 'XX' avatar monogram (#10958)
Printed emails omitted message headers and used minimal margins (#10567)
Compose button did not work in tablet split-screen message view (#10753)
Accented subfolder names sorted to bottom instead of locale order (#10718)
Disabled font size setting appeared in General Settings search (#10756)
New mail notifications showed avatars when contact pictures were disabled (#10750)
Mail opening still used fade-in after animations were disabled (#1903)
Sidebar account-switching animations were too fast (#10480)