Threads and detach
When Settings → Appearance → Collapse same-thread messages in the list is on (the default), the list shows one row per conversation. The newest message is the row. Older members stack in the reader.
How threading works
Section titled “How threading works”Primail groups on References and In-Reply-To. It does not fall back to a matching subject, and it does not use a two-signal match plus a 30-day participant window.
That avoids joining unrelated mail that happens to share a subject. It can also leave related mail ungrouped when a sender omits reply headers.
Open members
Section titled “Open members”Click the row to open every message in that conversation from the mailbox that received it. O collapses all cards; ⇧O expands them. Settings → Appearance → Minimize old emails in thread view can collapse older cards to a one-line summary.
List shortcuts (Done, Pin, Snooze, spam, and the rest) apply to all members of the focused conversation. Actions on a single card inside the reader can stay on that message.
Detach
Section titled “Detach”If one card does not belong:
- Open the conversation.
- Open the overflow menu on that card (multi-message threads only).
- Choose Detach from thread.
The message becomes its own conversation on this Mac. The provider copy is not rewritten. There is no Undo for detach.
Agents can use thread_merge. The current app has no
Merge threads command, no multi-select merge, and no subject
winner picker. Do not try a GUI merge procedure.
What is not here
Section titled “What is not here”- A copy-link control for a conversation
- Cross-device sync of detach
- A stable public URL for a conversation
Detach stays on this Mac. Another mail app still shows the provider’s threading.
Agents
Section titled “Agents”thread_get, thread_detach, and thread_merge are registered.
See the MCP tool reference.