Setup is the real cost here — two APIs to enable, an OAuth client to create, a script to run for the refresh token — and it buys you the thing hosted mail connectors cannot offer, which is that the credentials never leave your project. What you get for it is mail you can search in Gmail's own query syntax and act on in the same turn.
A Gmail and Google Calendar server that runs on credentials you create yourself. You enable the two APIs in a Google Cloud project, create an OAuth client, and exchange it for a refresh token the server then uses — so the access granted is exactly the scopes you approved.
- Recent inbox mail listed, with filtering
- Search across mail using Gmail's own query syntax
- Mail sent, including CC and BCC recipients
- Labels changed on a message — archive, trash, mark read or unread
- Calendar events over the same credentials: listed by date range, created with attendees, updated and deleted
Node.js, plus a Google Cloud project with the Gmail API and Google Calendar API enabled and an OAuth client whose redirect URI is a localhost callback. A bundled script runs the browser consent once on that callback and writes the refresh token. Consent covers gmail.modify, gmail.send and calendar.