spamd is a daemonized version of spamassassin.
spamd (obspamd) is also a fake sendmail(8)-like daemon which rejects false mail.
When using the SpamAssassin module to edit the blacklist and whitelist data, a HUP signal is sent to spamassassin-related processes, which completely kills the OpenBSD spamd process.
If you are not using the daemonized version of spamassassin with amavisd, a workaround is to remove spamd from the processes parameter in the Webmin SpamAssassin module configuration file.
# vi /usr/local/etc/webmin/spam/config ------------------------------ cut here ------------------------------ processes=amavisd ------------------------------ cut here ------------------------------