qmail-smtpd does not know if a user exists. Lots of resources are wasted by scanning mail for spam and viruses for addresses that do not exist anyway. A replacement smtpd written in Perl could use this module to quickly verify that a local email address is (probably) actually in use. This module comes with a daemon program called qmail-deliverabled and a module called Qmail::Deliverable::Client that copies the entire public interface, but queries the daemon. Typically, the daemon runs as the root user, and the client is used by the unprivileged smtpd.
Binary packages can be installed with the high-level tool pkgin (which can be installed with pkg_add) or pkg_add(1) (installed by default). The NetBSD packages collection is also designed to permit easy installation from source.
The pkg_admin audit command locates any installed package which has been mentioned in security advisories as having vulnerabilities.
Please note the vulnerabilities database might not be fully accurate, and not every bug is exploitable with every configuration.
Problem reports, updates or suggestions for this package should be reported with send-pr.