Changes in Thunderbird 91

accounts API

• list([includeFolders]), get(accountId, [includeFolders]) and getDefault([includeFolders]) now have an optional parameter includeFolders to specify if the returned MailAccount objects should populate the folders property. Defaults to true

addressbooks API

• added remote property to AddressBookNode

browserAction API

• added support for the tabstoolbar location, usable in the default_area manifest key

cloudFile API

• added the tab parameter to onFileDeleted

• added the tab parameter to onFileUpload

• added the tab parameter to onFileUploadAbort

compose API

• all attachment related functions and events now also require the compose permission

contacts API

• added remote property to ContactNode

• second parameter to quickSearch([parentId], queryInfo) can now be a qeuryInfo object instead of just a string, to define mored detailes query parameters

folders API

• delete(folder) now requires the messagesDelete permission

• added new function getParentFolders(folder, [includeSubFolders]) to get information about the current hierarchy level and parent folders

• added new function getSubFolders(folderOrAccount, [includeSubFolders]) to get information about subfolders

• the create(parent, childName) function can now create folders in the root of an account, by specifying an account instead of a folder as first parameter

• added move(sourceFolder, destination) function

• added copy(sourceFolder, destination) function

• added getFolderInfo(folder) function and MailFolderInfo type to obtain additional folder information like totalMessageCounts or unreadMessageCounts

• added onCreated event

• added onRenamed event

• added onMoved event

• added onCopied event

• added onDeleted event

• added onFolderInfoChanged event

identities API

• added identities API (including create/delete/update functions and onCreated/onDeleted/onUpdated events)

• added signature and signatureIsPlainText to MailIdentity

mailingLists API

• added remote property to MailingListNode

mailTabs

• the MailTab object now includes a viewType property, supporting the values ungrouped, groupedByThread and groupedBySortType

• the update([tabId], updateProperties) function allows to set the new viewType property

messages

• query(queryInfo) now searches all messages and not only the indexed ones

• added support for negative tag search to query(queryInfo)

• added includeSubFolders to search folders recursivly with query(queryInfo)

• added onUpdated

• added onMoved

• added onCopied

• added onDeleted

• added the messagesDelete permission to guard delete(messageIds, [skipTrash])

tabs API

• added type property to Tab, supporting addressBook, calendar, calendarEvent, calendarTask, chat, content, mail, messageCompose, messageDisplay, special and tasks

• added type as supported property of the queryInfo parameter of query(queryInfo)

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Bugzilla list of fixed WebExtension API defects in Thunderbird 91.