3.4 KiB

Lacre Project

Lacre (wax seal in Portuguese) is an add-on for Postfix that automatically encrypts incoming email before delivering it to recipients' inbox for recipients that have provided their public keys.

Lacre is a fork and continuation of the original work on gpg-mailgate project. It is still actively developed and should be considered as beta -- with all APIs and internals being subject to change. Please only use this software if you know GnuPG well and accept occasional failures.

How it works

Lacre is a content filter. This means, that when Postfix receives a message, it "forwards" that message to Lacre and if Lacre delivers it to a given destination, the message arrives to recipient's inbox.

After receiving the message, Lacre does the following:

  1. If message already is encrypted, it just delivers the message immediately.
  2. Checks the list of recipients, finds their public keys if any were provided.
  3. Encrypts message if possible.
  4. Delivers the message.

Work on this project in 2021 was funded by NGI Zero PET for which we are very thankful.

Made possible thanks to:


For installation instructions, please refer to the included INSTALL file.

Planned features

  • Correctly displays attachments and general email content; currently will only display first part of multipart messages
  • Public keys are stored in a dedicated gpg-home-directory
  • Encrypts both matching incoming and outgoing mail (this means gpg-mailgate can be used to encrypt outgoing mail for software that doesn't support PGP or S/MIME)
  • Easy installation
  • People can submit their public key like to any keyserver to gpg-mailgate with the gpg-mailgate-web extension
  • People can send an S/MIME signed email to register@yourdomain.tld to register their public key
  • People can send their public OpenPGP key as attachment or inline to register@yourdomain.tld to register it

See also: lacre-webgate -- a web interface allowing any user to upload PGP keys so that emails sent to them from your mail server will be encrypted

This is forked from the original project at


This is a combined work of many developers and contributors. We would like to pay honours to original gpg mailbox developers for making this project happen, and providing solid solution for encryption emails at rest: