Built on Open Source

Truepost is built on open source, the same way Security Architects and eRacks Systems work - we use it, and we say where it came from. This page lists the projects and open data Truepost runs on, what each one does for you, and its license.

Open data

When you sign in with a password, Truepost finds your mail server the way Thunderbird does: well-known providers first, then your domain's own DNS records, then Mozilla's ISPDB - the open database of mail settings behind Thunderbird's setup wizard. Only your domain is looked up, never your address or your password.

ProjectUsed forLicense
Mozilla ISPDBfinding your mail server when you sign in with a passwordMPL-2.0
MaxMind GeoLite2the network and country a message really came fromGeoLite2 End User License Agreement

This product includes GeoLite2 data created by MaxMind, available from https://www.maxmind.com.

The server

ProjectUsed forLicense
FastAPIthe web APIMIT
Starletteweb framework coreBSD-3-Clause
Uvicornweb serverBSD-3-Clause
AnyIOworker threads behind the APIMIT
IMAPClientreading and filing mail over IMAPBSD-3-Clause
dnspythonDNS lookups for mail server discoveryISC
HTTPXHTTP requestsBSD-3-Clause
RequestsHTTP requestsApache-2.0
Beautiful Soupreadable text and links from HTML-only mailMIT
GeoIP2 / MaxMind DB readerreading the GeoLite2 dataApache-2.0
pywebpushlogin-code alerts to your phone with Truepost closedMPL-2.0
cryptographykeys and signing for those alertsApache-2.0 or BSD-3-Clause
google-authGmail sign-inApache-2.0
GnuPGopening PGP-encrypted mail and checking signaturesGPL-3.0-or-later (run as a separate program)

Spam flags also read the verdicts your own mail server adds, such as Apache SpamAssassin's (Apache-2.0). Truepost reads those headers; it does not include SpamAssassin.

The app

ProjectUsed forLicense
Sveltethe Truepost web appMIT
Vitebuilding the appMIT

The original app and testing

ProjectUsed forLicense
Fletthe original Truepost appApache-2.0
Playwrightbrowser testsApache-2.0
pytesttestsMIT

Licenses are taken from each project's own package information and repository, September 2026.