Security at Sincerely
The short version: we never touch your email, we hold the minimum data needed to render signatures, and the blast radius of everything is deliberately small.
We never read your email
Sincerely holds no Gmail message scopes and does not route, relay or process your mail. Signatures are installed client-side into Gmail's own settings. There is no server in our architecture that an email passes through.
Data isolation
Every table in our database enforces row-level security, so one organisation's data is invisible to another's queries at the database layer, not just in application code. Each mutation is additionally authorised by an explicit permission check in the application.
Google tokens
Where an admin connects the Google Directory, the refresh token is encrypted at rest, never exposed to any client, never logged, and revoked with Google the moment you disconnect.
Infrastructure
- Hosting on Vercel; data in Supabase (London, UK). TLS everywhere.
- Secrets live in server-side environment configuration only; the browser bundle is checked for leaked keys as part of the release checklist.
- Public endpoints are rate-limited; uploads are re-encoded through an image pipeline (nothing you upload is served byte-for-byte).
- Click tracking stores hashed IPs with a daily rotating salt, raw IPs are never written to disk.
Disclosure
Found something? Email [email protected]. We respond within 48 hours and fix confirmed issues fast.