Release Notes

Extension API: Compose API now supports editing messages and templates as new messages

Extension API: composeHtml is now exposed in MailIdentity

Extension API: windows.update and windows.create now support titlePreface

Extension API: new Accounts API functions: accounts.getDefault() and accounts.getDefaultIdentity(accountId)

Extension API: body and plainTextBody are now used as compose mode selectors in setComposeDetails and begin* functions in Compose API

Theme: removed the double border around the task description field on the Tasks tab

Account Manager: When deleting the last remaining account, the default account was not getting cleared and still pointed to the no-longer-existing account

OpenPGP: Verification of an inline signed message would fail if it contained leading whitespace

OpenPGP: Various other minor bug and stability fixes

Mail Window: Quickfilter bar buttons disappear when hovered on Windows 10 High Contrast Black theme

Theme: folder properties dialog contained black text on a black background in dark mode

Theme: recipient pills in compose window were not visible in high contrast dark theme on Windows 10

Extension API: browserAction buttons were not restored after restart if they were moved outside the default toolbar

Extension API: browser.compose.beginNew could not override identity plaintext setting

Extension API: browser.compose.beginForward was ignoring ComposeDetails

Extension API: browser.compose.setComposeDetails did not properly handle Windows-style line endings

Various security fixes

Thunderbird performs sluggishly on macOS Big Sur