Shadow

Removed in version 2.4.0 (CE).

Removed in version 3.0.0 (Pro).

Warning

This plugin has been removed. Use PAM instead.

Works at least with Linux and Solaris, but nowadays PAM is usually preferred to this.

This uses auth-worker processes:

passdb {
  driver = shadow
}

By default the auth-worker processes are run as dovecot user though, which normally doesn’t have access to /etc/shadow. If this is a problem, you can fix it with:

service auth-worker {
  # This should be enough:
  group = shadow
  # If not, just give full root permissions:
  #user = root
}

If there are only a few users and you’re using /etc/shadow file, there’s really no need to use auth-workers. You can disable them with:

passdb {
  driver = shadow
  args = blocking=no
}