This patch makes it possible to add addresses like spammer@ to the qmail
badmailfrom control file.         http://www.wolfermann.org/djbware.html

--- qmail-smtpd.c.orig	Mon Jun 15 12:53:16 1998
+++ qmail-smtpd.c	Mon Dec 11 09:28:10 2000
@@ -203,8 +203,10 @@
   if (!bmfok) return 0;
   if (constmap(&mapbmf,addr.s,addr.len - 1)) return 1;
   j = byte_rchr(addr.s,addr.len,'@');
-  if (j < addr.len)
+  if (j < addr.len) {
     if (constmap(&mapbmf,addr.s + j,addr.len - j - 1)) return 1;
+    if (constmap(&mapbmf,addr.s,j + 1)) return 1;
+  }
   return 0;
 }