LocalInbox checks a message when you press Send and asks once if something looks wrong: it says “attached” with nothing attached, a reply goes to more than 10 people, it holds a card number, IBAN, password or API key, an address looks like one you know but isn't, or a {name} or XXX is still there to fill in. You can Fix it, Send Anyway, or choose Don't Warn for that recipient. The checks run on your Mac.
What it checks
- Forgotten attachments: the message mentions one (“attached”, “PFA”, “anbei”, “ci-joint”…) and nothing is attached.
- Large reply-alls: a reply goes to more people than your limit, 10 unless you change it, or adds people from outside the conversation.
- Card numbers, passwords and keys: card and IBAN numbers, Aadhaar and PAN, and what looks like a password or an API key.
- Unfamiliar recipients: an address that looks like one you've written to, or a first message to someone at a company where you write to someone else.
- Missing subject and placeholders: no subject, or something left to fill in, such as {name}, [date] or XXX.
One sheet, once per send
- Everything the checks find appears together, in one sheet: “Before you send”.
- Fix, or Return or Esc, goes back to the message as it was, so a reflex never sends it.
- Send Anyway sends it.
- Don't Warn for … sends it and stops these checks asking about those recipients.
- Send Later is checked too: the checks ask now, while the draft is in front of you.
Your choice
Each check can be turned off in Settings › Composing › Before sending, where you also set the reply-all limit and reset anyone you chose Don't Warn for.
Questions
Does it read my message on a server?
No. The checks run on your Mac when you press Send. LocalInbox has no server, and a message goes only to your mail provider, for sending.
Does it need Apple Intelligence?
No. The checks work on any Mac with macOS 15 or later.
Will it stop me sending?
Never for good. It asks once per send, and Send Anyway always sends. If a check doesn't suit you, turn it off in Settings › Composing › Before sending.
Is it on iPhone and iPad too?
Yes, the same checks, in Settings › Composing › Before sending. Press and hold Send on a reply for Send & Archive. LocalInbox for iPhone and iPad is on the App Store, with the same licence: https://localinbox.app/iphone