Cangtian Mail Assistant
A private, single-user command-line utility that automatically organizes Gmail messages by applying labels to them. It is operated by one individual for one Gmail account, and it is not offered as a commercial product or public service.
What this app does
The app has a single function: keeping the inbox of its one user tidy by sorting messages into four categories. It runs on a weekly schedule, and on each run it performs the following steps.
- Reads a limited window of recent inbox messages. It queries Gmail for messages received in the last seven days, retrieving the sender, subject line, timestamp, and a short text snippet of each message.
-
Classifies each message into exactly one category.
Every message is assigned a single label according to a fixed rule set, so that no
message ever carries two of these categories at once:
Invoices Work Subscriptions Notifications - Applies the label to the message. The chosen label is added to the message thread. The app only adds labels — it does not remove existing labels, and it does not move, archive, or delete anything.
- Skips messages that were already categorized. Messages that already carry one of the four labels are excluded from the query, so the app does not reprocess or duplicate work.
What this app never does
It does not send, reply to, forward, delete, or archive email. It does not download attachments. It does not create, modify, or delete Gmail filters or settings. It does not read mail outside the seven-day inbox window described above.
Google user data this app accesses
The app operates on a single Gmail account, belonging to the person who also operates the app. The table below sets out every category of Google user data it reads or writes, and why that access is required.
| Google user data | Why it is required | Where it is processed |
|---|---|---|
| Message metadata — sender, subject, timestamp, and a short text snippet of recent inbox messages (last 7 days) | Required to determine which of the four categories each message belongs to | In memory on the operator's own computer, during the run only |
| Label names and identifiers | Required to look up the four existing labels and to apply the correct one | In memory on the operator's own computer, during the run only |
| Message labels (write access) | Required to add the chosen category label to each message thread | Written directly to Gmail through the Gmail API |
Google API Limited Use statement. App's use of information received from Gmail APIs will adhere to Google's Limited Use Requirements.
No sharing, no resale, no advertising
Google user data is never sold, rented, transferred, or disclosed to any third party. It is not used for advertising, profiling, or training machine-learning models. No data is sent to any analytics, telemetry, or crash-reporting service.
How to revoke access
Access can be revoked at any time from the Google Account permissions page at myaccount.google.com/permissions. Revoking access immediately and permanently stops all further API activity by this app. Full details are set out in the Privacy Policy.
App details
- App name
- Cangtian Mail Assistant
- Purpose
- Personal Gmail labeling utility, operated for a single user account
- Intended users
- One user — the operator of the app. There is no public sign-up and no other users.
- Platform
- Command-line application running locally on the operator's computer
- Google APIs used
- Gmail API (read message metadata; apply labels)
- Support contact
- cangtian606@gmail.com
- Last updated
- 4 October 2026