New:Remote feature flags can be viewed and managed in General Settings (#11457)Changed:Modernized 'Sending Mail' settings screen (#11041)Manage Folders settings moved from account drawer to Account settings under Folders (#11679)Folder display, sync, and notification settings are split into separate menus (#11763)Fixed:Donation appeal dialog could display multiple times (#11677)Account profile avatars were not imported from K-9 Mail (#10864)Contributors:Thanks to: @coreycb, @dani-zilla, @dougsparling, @itsSiide, @JustNotesa, @rafaeltonholo, @shamim-emon, @stephenking314, @wmontweNew Contributors:@dougsparling made their first contribution in #11847Full Changelog: THUNDERBIRD_25_0b2...THUNDERBIRD_26_0b1