List Folders

Returns the full folder/label set across the tenant's read-enabled mailbox configurations. When configCode query param is omitted, returns folders for every accessible config (owned or shared). When configCode is provided (repeatable), narrows to those configs. Set systemFoldersOnly=true to return only provider-system folders (Inbox/Sent/Drafts/Archive/Junk/Trash/Outbox/GmailPromotionalCategory) — combined-mailbox views use this. Each folder includes per-folder total and unread counts.