SMF·NEWTON-MAIL
Can a prompt replace Newton Mail?
Email — email clients and hosted mail
Exhibit tracking slip
Verdict
Read receipts are the feature Newton is remembered for, and they are also the feature this build has to think hardest about, because the mechanism is a tracking pixel — the same thing every decent client now blocks by default, including this one on incoming mail. Implementing it is easy; implementing it honestly, off by default and disclosed to the recipient, is the interesting design problem. The client underneath is the same fortnight of IMAP work as every other entry in this category.
Exhibit A — The prompt
Received on31.07.2026Build a desktop email client with send-later, snooze, and read receipts implemented honestly.
Account: one IMAP and SMTP account, credentials in the OS keychain, password and OAuth both supported. Incremental resumable sync, SQLite index with full-text search, standards-based threading, HTML rendered in a sandbox with remote images blocked by default.
Send later: hold the message in a local outbox with its scheduled time, submit through SMTP when it arrives. The scheduler only runs while the application does, so show the next scheduled send prominently and warn on quit if something is pending. A silent missed send is worse than no feature.
Snooze: move the message to a hidden server folder and return it to the inbox at the chosen time, driven by a local timer with the same caveat displayed.
Read receipts, which is the distinguishing feature and the one that needs care:
- Off by default, enabled per message in the composer, never globally by default.
- Implement as a uniquely keyed 1x1 image served from a host the user configures, plus a Disposition-Notification-To header for clients that honour the standard.
- Every message sent with a receipt must carry a visible line in its body stating that read tracking is enabled. Not a setting, not a footnote — a line the recipient sees. A tool that tells you when someone opened your mail without telling them is doing something to a person who did not agree to it, and the build should not offer that.
- Record only a timestamp and a coarse open count against the message. Do not record IP addresses, user agents, locations, or anything else the request happens to carry.
- Report the result honestly: show "opened", "not opened", or "unknown — the recipient's client blocks remote images", and never present the third as the second. Most modern clients proxy or block images, so unknown is the common outcome and the interface should expect it.
Incoming mail: block remote content by default and show a badge when a message contained tracking pixels, with the sending domain named. The same mechanism, seen from the other side.
Also build: drafts saved server-side, attachments, mbox export.
Out of scope: mobile apps and push, running a mail server, team features, and any tracking beyond the disclosed open receipt described above.Opening prefills the prompt — press enter to run it.
Exhibit B — What you lose
- B.1 push notifications and mobile clients
- B.2 receipts that survive a recipient whose client blocks remote images — which is most of them now
- B.3 sync of snoozes and scheduled sends between devices
- B.4 the integrations that connected Newton to task and note apps
Prior art
Exhibit C — Why people still pay: mail infrastructure, integrations, and client polish
Because the client has to be everywhere the mail is. Newton's cross-platform presence and push were the product; the receipts were the reason people noticed it.
Questions
Is there anything to migrate from Newton?
Mail is on the server. Newton's snoozes and scheduled sends lived in its own service and are gone when the subscription ends, so check for anything pending before you leave — that is the one thing genuinely at risk in this migration.
Why disclose the read receipt in the message?
Because the alternative is tracking someone who never agreed to it, using the exact mechanism this same client blocks when it arrives in your own inbox. Disclosure keeps the feature usable for the legitimate case — knowing whether an important message landed — without the tool being a tracker.
What does it cost to run?
Nothing for the client. The receipt pixel needs somewhere to be served from, which is any small host you already have, so a few dollars a month at most and nothing if you already run a server.
What is the one thing that does not survive the rebuild?
Receipts that work. Apple Mail Privacy Protection and most webmail providers now fetch or block remote images on the recipient's behalf, which means a receipt either never fires or fires immediately regardless of whether a human looked. The feature was more reliable when Newton launched than it is today.
Related tools
Receipt