OpenBSD's spamd(8) is a spam deferral daemon which rejects false mail in a very efficient way.
A variety of databases exist which can be specified in the /etc/mail/spamd.conf file, and loaded using spamd-setup(8).
However, most of the publicly available lists providing access to the whole database in a downloadable file have now shut down. If you were using the nixspam list previously mirrored here, you should remove it.