If you see messages like this:
spamd[3279]: prefork: server reached --max-clients setting, consider raising it
You'll probably try raising the --max-clients setting, only to find that that switch does not exist. This was a typo; the correct settting is called --max-children.
[http://mail-archives.apache.org/mod_mbox/spamassassin-users/200601.mbox/%3C43CE9A46.3030607@evi-inc.com%3E See this mail from Matt Kettler] for more details.
[http://issues.apache.org/SpamAssassin/show_bug.cgi?id=4586 This bug] was fixed in SA 3.1.1.