Socketmap server to integrate uffd mail aliases with postfix

uffd has features that rely on mail aliases. To make those mail aliases work, it provides an API to lookup alias addresses for a given address. uffd-socketmap uses this API to integrate alias lookup with MTAs that support the socketmap protocol, like sendmail and postfix.

uffd-socketmap can be run manually. For production deployments, use the provided debian packages. Add our package mirror to /etc/sources.list:

deb https://packages.cccv.de/uffd bullseye main

Then download cccv-archive-key.gpg and add it to the trusted repository keys in /etc/apt/trusted.gpg.d/. Afterwards run apt update && apt install uffd-socketmap to install the package.

Set the API url and secret in /etc/uffd-socketmap-postfix.conf, enable and start uffd-socketmap-postfix.socket. Then configure Postfix, e.g. by adding the following lines to /etc/postfix/main.cf:

# Note that postfix runs in a chroot (/var/spool/postfix) and paths are
# relative to that!
virtual_alias_maps = socketmap:unix:/uffd-socketmap.sock:virtual
# Defaults to $virtual_alias_maps, which does not work here, so unset it
virtual_alias_domains =