Smart Inbox
Split your Postbox inbox into People, Newsletters, Notifications, and Receipts — a deterministic classifier first, AI refinement for the ambiguous middle, off by default, and a per-sender override that's remembered.
Smart Inbox groups your personal Postbox inbox into sections by what kind of mail each thread is — People, Newsletters, Notifications, Receipts, and Everything else — so real person-to-person mail stops competing with order confirmations and list broadcasts.
It's a display grouping only: categorizing a thread never moves, files, marks, or modifies mail. Turn the grouping off and every thread is right where it was.
Smart Inbox is opt-in. The inbox shows a single list until you turn on Group by category. The AI-refinement half also needs the ai feature flag (with an LLM provider configured — see Feature flags); without it, mail is grouped by the deterministic heuristic alone and anything the heuristic can't place lands in Everything else.
Turning it on
Open your Postbox inbox and click the Group by category button in the inbox header (it toggles back with Show a single list). Grouping is inbox-only — every other folder stays a normal list.
When it's on, threads are bucketed into sections in a fixed order, People first:
| Section | What lands here |
|---|---|
| People | Mail from a known human correspondent — someone in your personal address book, or someone you've written to before — with no automated markers. |
| Newsletters | Broadcast/list mail: anything carrying a List-Unsubscribe header or Precedence: bulk/list. |
| Notifications | Automated / system senders — no-reply@, notifications@, alerts@, security@, and similar. |
| Receipts | Transactional mail: receipts, invoices, order confirmations, payment and subscription-renewal notices (detected from the subject). |
| Everything else | Anything not classified above — including threads the classifier hasn't reached yet, so nothing is ever hidden. |
Empty sections are skipped, and each section header collapses so you can fold away a bucket you don't want to see; the collapsed state is remembered as you move around during the session.
How a thread is classified
Classification runs on the latest inbound message of a thread (not your own replies) in two stages, mirroring the Reply Queue:
- A deterministic heuristic first. Pure, fast rules decide the clear cases: a
List-Unsubscribeheader or bulkPrecedencemakes it a Newsletter; receipt/invoice/order keywords in the subject make it a Receipt; an automated-sender local-part (no-reply,notifications,alerts, …) makes it a Notification; a known human correspondent with none of those markers is a Person. Genuinely ambiguous mail is left undecided. - AI refinement for the ambiguous middle. Only the mail the heuristic couldn't place is handed to a cheap-tier LLM pass, behind the same AI gate as the rest of Postbox AI. It fails soft: if the
aiflag is off, no provider is configured, or the call errors, the thread keeps its deterministic label (or falls back to Everything else). The message is treated as untrusted input, and the model only labels — it never sends, moves, or edits anything.
Classification happens when new mail is delivered to the inbox. A one-time backfill can also label your most recent existing inbox threads.
Recategorize as…
If Smart Inbox files a sender wrong, open the thread's overflow menu and pick Recategorize as… (Person / Newsletter / Notification / Receipt / Other). Your choice:
- Always wins over both the heuristic and the AI — it's authoritative.
- Is remembered per sender. The override is keyed to that sender's address, so future mail from them lands in the same section without another classification pass.
To change it back, recategorize the thread again.
Smart Inbox ships with Postbox (postbox or mail.external). The deterministic grouping and your per-sender overrides work on their own; the AI refinement of ambiguous senders requires the ai feature flag. See the desktop Notify me about → People & important only option in Postbox settings for how categories can also quiet your notifications.