Remail was written to sidestep the hard-to-solve problem of sending encrypted mail to multiple people, some of whom may prefer to use GnuPG, some PGP from Symantec, while others use S/MIME from corporate-issued CAs that are not in universal CA trust stores.
Remail accepts both S/MIME and PGP-encrypted email sent to a single address, decrypts it on the back-end, and then re-encrypts it to individual list subscribers using whichever is their preferred scheme for exchanging encrypted email.
For more information on this project, please see the official Remail git repository.
Kernel.org uses remail for discussions that need to happen around coordinated response to embargoed security vulnerabilities. The service itself runs on a dedicated VM inside a private cloud cluster that has no direct access from the Internet – it can only be accessed via the VPN used by IT operations personnel. Any administrative access to that internal remail system requires 2-factor authentication. Any off-site backups performed on that system are PGP-encrypted with a unique symmetric key before they are uploaded to external storage.
For transparency purposes, conversations exchanged between parties using encrypted email are logged on the internal remail system in order to provide a sanitized public discussion archive once embargoes are lifted.
If you would like to request your own remail list, please contact firstname.lastname@example.org.