If you start seeing Status 11 errors to pop up in qmail-smtpd whenever a message came in from a domain, The SPF records uses colons for delimiters instead of spaces, so the lack of spaces, and possibly other syntax problems, in an SPF record will cause smtpd to exit abnormally and put the status 11 message in your qmail-smtpd log and a signal 11 error in /var/log/messages. I worked around this problem by adding this in in /etc/tcp.smtp,SPFBEHAVIOR="0"

Special thanks to Lonnie Burgess