"Delivery event tracking" section on the core Email Sending settings page (/admin/settings/email-sending) — the unified, registry-driven admin panel from the universalization spec (dev_docs/specs/ 2026-07-26-email-event-tracking-universalization-spec.md §5). One row per EventTrackerRegistry.trackers/0 entry; a new provider (Mailgun, …) appears automatically once it registers, no panel code to touch.

Replaces the polling controls that used to live in the two separate provider settings sections (amazon_ses_sqs, brevo_events) — see those modules' moduledocs for what stayed behind (transport/identity config, not polling).

The expandable row

Every row expands to its own settings: the polling interval (generic — every tracker has one) plus whatever the tracker names through EventTracker.settings_component/1. SES points that at SettingsSections.AmazonSesSqs, which used to be a third, sibling section on this page — a peer of this table while actually being the detail of one of its rows, duplicating its "is collection on" answer and offering no clue which row it belonged to.

Expansion is an assign (@expanded, a MapSet of provider_kinds), not a <details> or a daisyUI collapse checkbox: LiveView's morphdom patch resets the DOM-only open state of both, so any row would snap shut on the next poll-count refresh. Like the accounts dialog, the set is re-resolved against fresh rows in assign_rows/1 — the ONE place rows are built — so a provider that disappeared (a tracker dropped by a deploy) cannot leave an expanded row rendering against nothing.

"Poll now" vs poll_cycle/1

EventTracker.poll_cycle/1's own moduledoc anticipated this button calling it directly (a synchronous, in-process cycle). This panel calls each tracker's poll_now/0 instead (see EventTrackerRegistry's duck-typed "Manager API"): it already exists, already handles the "force a poll even while the toggle is off" case explicitly, and enqueues via Oban rather than blocking the LiveView process for a network round trip. poll_cycle/1 stays defined (still satisfies the behaviour) but unused here — a deliberate choice, not an oversight.