Problem: In accounts with many labels and nested folders, the sidebar becomes long enough that Inbox, Sent, Spam and Trash disappear above the fold. Navigating back requires scrolling up, which breaks the flow when triaging mail.

Proposal: Make the core mailbox entries sticky at the top of the sidebar while the label/folder list scrolls beneath them. Add a "favourite" (pin) flag for any folder or label, so frequently used ones sit in the same fixed block, reorderable by drag-and-drop. Optionally allow collapsing the scrollable section.

Benefit: Faster navigation for power users with heavy labelling setups, fewer mis-clicks, and consistency with the behaviour users expect from modern mail clients.