I bought a new machine and can't get Plan 9 from Bell Labs to boot so I've installed 9front.  It works great and is very fast.  I've configured smtpd on the machine and it is getting messages but they're being blocked:

Feb 21 10:58:38 Disallowed yahoo.com!gary (sonic307-3.consmr.mail.bf2.yahoo.com/74.6.134.42) to blocked name mydomain.com!gary

Why am I getting blocked when receiving mail?  I know I've missed something. 

Thanks.