diff -u qmail-1.03.orig/qmail-smtpd.c qmail-1.03/qmail-smtpd.c
--- qmail-1.03.orig/qmail-smtpd.c	2004-03-17 22:28:39.029920888 +0100
+++ qmail-1.03/qmail-smtpd.c	2004-03-17 22:30:45.706663096 +0100
@@ -153,6 +153,7 @@
 void err_brt() { out("550 sorry, this message is not deliverable (#5.7.1)\r\n"); }
 void err_bmt() { out("533 sorry, your envelope recipient has been denied (#5.7.1)\r\n"); }
 void err_nogateway() { out("553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)\r\n"); }
+void err_dns() { out("453 temporary problem with dns\r\n"); }
 void err_badbounce() { out("550 sorry, bounce messages should have a single envelope recipient (#5.7.1)\r\n"); }
 #ifdef TLS
 void err_nogwcert() { out("553 no valid cert for gatewaying (#5.7.1)\r\n"); }
@@ -447,6 +448,7 @@
   int r;
   r = rcpthosts(addr.s,str_len(addr.s));
   if (r == -1) die_control();
+  if (r == -2) err_dns();
   return r;
 }
 
diff -u qmail-1.03.orig/rcpthosts.c qmail-1.03/rcpthosts.c
--- qmail-1.03.orig/rcpthosts.c	2004-03-17 22:28:51.881967080 +0100
+++ qmail-1.03/rcpthosts.c	2004-03-17 22:31:04.836754880 +0100
@@ -6,11 +6,16 @@
 #include "constmap.h"
 #include "stralloc.h"
 #include "rcpthosts.h"
+#include "dns.h"
+#include "ipalloc.h"
+#include "ipme.h"
 
 static int flagrh = 0;
 static stralloc rh = {0};
 static struct constmap maprh;
 static int fdmrh;
+static int flagrmxl = 0;
+static stralloc rmxl = {0};
 
 int rcpthosts_init()
 {
@@ -19,6 +24,8 @@
   if (!constmap_init(&maprh,rh.s,rh.len,0)) return flagrh = -1;
   fdmrh = open_read("control/morercpthosts.cdb");
   if (fdmrh == -1) if (errno != error_noent) return flagrh = -1;
+  flagrmxl = control_readfile(&rmxl, "control/relaymxlookup", 0);
+  if (flagrmxl == -1) if (errno != error_noent) return flagrh = -1;
   return 0;
 }
 
@@ -29,6 +36,8 @@
 int len;
 {
   int j;
+  static ipalloc ip = {0};
+  unsigned long random;
 
   if (flagrh != 1) return 1;
 
@@ -56,5 +65,27 @@
       }
   }
 
+  if (flagrmxl == 1) {
+    random = now() + (getpid() << 16);
+    switch (dns_mxip(&ip,&host,random)) {
+      case DNS_MEM:
+      case DNS_SOFT:
+        return -2;
+      case DNS_HARD:
+        return 0;
+      case 1:
+        if (ip.len <= 0) return 0;
+      default:
+        break;
+    }
+  
+    if(ip.len >= 1) {
+      int i;
+      for (i = 0;i < ip.len;++i)
+        if (ipme_is(&ip.ix[i].ip))
+          return 1;
+    }
+  }
+
   return 0;
 }