diff -Naur qmail-1.03/Makefile qmail-1.03.patched/Makefile
--- qmail-1.03/Makefile	1998-06-15 06:53:16.000000000 -0400
+++ qmail-1.03.patched/Makefile	2002-12-12 13:44:07.168951000 -0500
@@ -1542,7 +1542,7 @@
 	received.o date822fmt.o now.o qmail.o cdb.a fd.a wait.a \
 	datetime.a getln.a open.a sig.a case.a env.a stralloc.a \
 	alloc.a substdio.a error.a str.a fs.a auto_qmail.o  `cat \
-	socket.lib`
+	socket.lib` dns.o `cat dns.lib`
 
 qmail-smtpd.0: \
 qmail-smtpd.8
diff -Naur qmail-1.03/qmail-smtpd.c qmail-1.03.patched/qmail-smtpd.c
--- qmail-1.03/qmail-smtpd.c	1998-06-15 06:53:16.000000000 -0400
+++ qmail-1.03.patched/qmail-smtpd.c	2002-12-12 14:43:40.794130000 -0500
@@ -23,6 +23,7 @@
 #include "timeoutread.h"
 #include "timeoutwrite.h"
 #include "commands.h"
+#include "dns.h"
 
 #define MAXHOPS 100
 unsigned int databytes = 0;
@@ -36,11 +37,16 @@
   return r;
 }
 
-char ssoutbuf[512];
+char ssoutbuf[512], sserrbuf[512];
 substdio ssout = SUBSTDIO_FDBUF(safewrite,1,ssoutbuf,sizeof ssoutbuf);
+substdio sserr = SUBSTDIO_FDBUF(safewrite,2,sserrbuf, sizeof sserrbuf);
 
 void flush() { substdio_flush(&ssout); }
+void flusherr() { substdio_flush(&sserr); }
 void out(s) char *s; { substdio_puts(&ssout,s); }
+void err(s) char *s; { substdio_puts(&sserr,s); }
+
+stralloc mailfrom = {0};
 
 void die_read() { _exit(1); }
 void die_alarm() { out("451 timeout (#4.4.2)\r\n"); flush(); _exit(1); }
@@ -49,8 +55,6 @@
 void die_ipme() { out("421 unable to figure out my IP addresses (#4.3.0)\r\n"); flush(); _exit(1); }
 void straynewline() { out("451 See http://pobox.com/~djb/docs/smtplf.html.\r\n"); flush(); _exit(1); }
 
-void err_bmf() { out("553 sorry, your envelope sender is in my badmailfrom list (#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_unimpl() { out("502 unimplemented (#5.5.1)\r\n"); }
 void err_syntax() { out("555 syntax error (#5.5.4)\r\n"); }
 void err_wantmail() { out("503 MAIL first (#5.5.1)\r\n"); }
@@ -58,7 +62,79 @@
 void err_noop() { out("250 ok\r\n"); }
 void err_vrfy() { out("252 send some mail, i'll try my best\r\n"); }
 void err_qqt() { out("451 qqt failure (#4.3.0)\r\n"); }
+void err_smf() { out("451 DNS temporary failure (#4.3.0)\r\n"); }
+
+char *remoteip;
+char *remotehost;
+char *remoteinfo;
+char *local;
+char *relayclient;
+char *nodnscheck;
+
+void err_prefix(stralloc *from) {
+  err("qmail-smtp: ");
+  err(remoteip);
+  err("=");
+  err(remotehost);
+  if (from->len) {
+    err("; ");
+    err(from->s);
+  }
+  err(", ");
+}
+
+void err_suffix() {
+  err("\n");
+  flusherr();
+}
+
+void err_bmf(stralloc *from) {
+  err_prefix(from);
+  err("On badmailfrom");
+  err_suffix();
+  out("553 sorry, your envelope sender is in my badmailfrom list (#5.7.1)\r\n");
+}
+
+void err_nogateway(stralloc *from, stralloc *to) {
+  err_prefix(from);
+  err("Not in rcpthost: ");
+  err(to->s);
+  err_suffix();
+  out("553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)\r\n");
+}
+
+void err_relay(stralloc *from, stralloc *to) {
+  err_prefix(from);
+  err("Tried to Relay: ");
+  err(to->s);
+  err_suffix();
+  out("553 we don't relay (#5.7.1)\r\n");
+}
+
+stralloc addr = {0}; /* will be 0-terminated, if addrparse returns 1 */
 
+void err_dnsbl(char *dnsbl, stralloc *dnsblrc) {
+  stralloc msg = {0};
+  stralloc_copys(&msg, "553 Blacklisted at ");
+  stralloc_cats(&msg, dnsbl);
+  stralloc_catb(&msg, "\r\n", 3);
+  out(msg.s);
+  msg.len -= 3;
+  stralloc_catb(&msg, "=", 1);
+  stralloc_cats(&msg, dnsblrc->s);
+  stralloc_0(&msg);
+  err_prefix(&addr);
+  err(msg.s + 4);
+  err_suffix();
+}
+
+void err_nomx()
+{
+  err_prefix(&addr);
+  err("No MX");
+  err_suffix();
+  out("553 No DNS MX record found\r\n");
+}
 
 stralloc greeting = {0};
 
@@ -71,22 +147,17 @@
 {
   out("214 qmail home page: http://pobox.com/~djb/qmail.html\r\n");
 }
+
 void smtp_quit()
 {
   smtp_greet("221 "); out("\r\n"); flush(); _exit(0);
 }
 
-char *remoteip;
-char *remotehost;
-char *remoteinfo;
-char *local;
-char *relayclient;
-
 stralloc helohost = {0};
 char *fakehelo; /* pointer into helohost, or 0 */
 
 void dohelo(arg) char *arg; {
-  if (!stralloc_copys(&helohost,arg)) die_nomem(); 
+  if (!stralloc_copys(&helohost,arg)) die_nomem();
   if (!stralloc_0(&helohost)) die_nomem(); 
   fakehelo = case_diffs(remotehost,helohost.s) ? helohost.s : 0;
 }
@@ -96,6 +167,12 @@
 int bmfok = 0;
 stralloc bmf = {0};
 struct constmap mapbmf;
+int rdblok = 0;
+struct constmap maprdbl;
+stralloc rdbl = {0};
+int dwlok = 0;
+struct constmap mapdwl;
+stralloc dwl = {0};
 
 void setup()
 {
@@ -131,12 +208,21 @@
   if (!remotehost) remotehost = "unknown";
   remoteinfo = env_get("TCPREMOTEINFO");
   relayclient = env_get("RELAYCLIENT");
+  nodnscheck = env_get("NODNSCHECK");
+  if (!nodnscheck) {
+    rdblok = control_readfile(&rdbl, "control/remotedomainblacklist", 0);
+    if (rdblok == -1) die_control();
+    if (rdblok)
+      if (!constmap_init(&maprdbl, rdbl.s, rdbl.len, 0)) die_nomem();
+    dwlok = control_readfile(&dwl, "control/nodnscheck", 0);
+    if (dwlok == -1) die_control();
+    if (dwlok)
+      if (!constmap_init(&mapdwl, dwl.s, dwl.len, 0)) die_nomem();
+  }
   dohelo(remotehost);
 }
 
 
-stralloc addr = {0}; /* will be 0-terminated, if addrparse returns 1 */
-
 int addrparse(arg)
 char *arg;
 {
@@ -216,10 +302,20 @@
   return r;
 }
 
+int addrrelay()
+{
+  char *s;
+
+  for (s = addr.s + addr.len; s-- > addr.s;)
+    if (*s == '@') break;
+  while(s-- > addr.s)
+    if (*s == '@' || *s == '%' || *s == '!') return 1;
+  return 0;
+}
+
 
 int seenmail = 0;
 int flagbarf; /* defined if seenmail */
-stralloc mailfrom = {0};
 stralloc rcptto = {0};
 
 void smtp_helo(arg) char *arg;
@@ -237,9 +333,63 @@
   seenmail = 0;
   out("250 flushed\r\n");
 }
+
+int dnscheck(stralloc *to)
+{
+  int i, j;
+  unsigned int random;
+  stralloc sa = {0};
+  ipalloc ia = {0};
+
+  dns_init(0);
+
+  if ((i = byte_rchr(to->s, to->len, '@')) < to->len) {
+    char *le, *ele;
+    i++;
+    /* First make sure it's not on the domain exclusion list */
+    if (dwlok) {
+      stralloc_copys(&sa, to->s + i);
+      stralloc_0(&sa);
+      for (ele = (le = dwl.s) + dwl.len; le < ele; le += str_len(le) + 1)
+	if (!case_diffs(sa.s, le)) return 1;
+    }
+    /* Look it up on any remote blacklist */
+    if (rdblok) {
+      for (ele = (le = rdbl.s) + rdbl.len; le < ele;) {
+	/* First check to see if domain is on blacklist */
+	stralloc_copys(&sa, to->s + i);
+	stralloc_cats(&sa, ".", 1);
+	stralloc_cats(&sa, le);
+	stralloc_0(&sa);
+	j = dns_ip(&ia, &sa);
+	if (j == DNS_MEM) die_nomem();
+	if (j == DNS_SOFT) { err_smf(); return 0; }
+	if (j != DNS_HARD) {
+	  /* Found it in the blacklist */
+	  char tmp[IPFMT];
+	  stralloc_copyb(&sa, tmp, ip_fmt(tmp, &ia.ix[0].ip));
+	  stralloc_0(&sa);
+	  err_dnsbl(le, &sa);
+          return 0;
+	}
+	le += str_len(le) + 1;
+      }
+    }
+    /* Now check for MX record */
+    random = now() + (getpid() << 16);
+    stralloc_copys(&sa, addr.s + i);
+    j = dns_mxip(&ia, &sa, random);
+    if (j == DNS_MEM) die_nomem();
+    if (j == DNS_SOFT) { err_smf(); return 0; }
+    if (j == DNS_HARD) { err_nomx(); return 0; }
+  }
+  return 1;
+}
+
 void smtp_mail(arg) char *arg;
 {
   if (!addrparse(arg)) { err_syntax(); return; }
+  if (!nodnscheck && !dnscheck(&addr)) return;
   flagbarf = bmfcheck();
   seenmail = 1;
   if (!stralloc_copys(&rcptto,"")) die_nomem();
@@ -247,17 +397,19 @@
   if (!stralloc_0(&mailfrom)) die_nomem();
   out("250 ok\r\n");
 }
+
 void smtp_rcpt(arg) char *arg; {
   if (!seenmail) { err_wantmail(); return; }
   if (!addrparse(arg)) { err_syntax(); return; }
-  if (flagbarf) { err_bmf(); return; }
+  if (addrrelay()) { err_relay(&mailfrom, &addr); return; }
+  if (flagbarf) { err_bmf(&mailfrom); return; }
   if (relayclient) {
     --addr.len;
     if (!stralloc_cats(&addr,relayclient)) die_nomem();
     if (!stralloc_0(&addr)) die_nomem();
   }
   else
-    if (!addrallowed()) { err_nogateway(); return; }
+    if (!addrallowed()) { err_nogateway(&mailfrom, &addr); return; }
   if (!stralloc_cats(&rcptto,"T")) die_nomem();
   if (!stralloc_cats(&rcptto,addr.s)) die_nomem();
   if (!stralloc_0(&rcptto)) die_nomem();
diff -Naur qmail-1.03/qmailDomainChecks.txt qmail-1.03.patched/qmailDomainChecks.txt
--- qmail-1.03/qmailDomainChecks.txt	1969-12-31 19:00:00.000000000 -0500
+++ qmail-1.03.patched/qmailDomainChecks.txt	2002-12-12 15:30:45.314624000 -0500
@@ -0,0 +1,50 @@
+README for qmail patches created by Gary Gendel
+
+I started this project because I wanted to utilize the domain-based
+blacklists from rfc-ignorant.org.  This required me to make patches to
+qmail-smtpd.c.  The code changes is pretty minor, but some of the code had
+to be shuffled to allow me to access some global variables that were declared
+later than I needed them.  I've released this code into the public domain, no
+restrictions.
+
+The patches add the following checks:
+1) Disallows '@', '%' and '!' in sender's name (Prevents relaying).  If any
+   found it is logged (stderr) and rejected.
+
+2) If NODNSCHECK environment variable is set then it skips the remainder
+   of the checks. Otherwise:
+
+3) It looks in controls/nodnscheck.  If the mail from domain is listed in the
+   file then it skips the remainer of the checks.  For example, aol.com shows
+   up in postmaster.rfc-ignorant.com and I actually get legitimate email
+   from there.
+
+4) It looks in controls/domainblacklist.  It does a domain blacklist lookup
+   on the mail from domain for each blacklist server in the file.
+   For example I list:
+
+   whois.rfc-ignorant.com
+   postmaster.rfc-ignorant.com
+   
+   If it is found on the list, it is logged (stderr) and rejected.
+
+5) The mail from domain is queried for a DNS MX or A record. If none exists
+   then it is logged (stderr) and rejected.
+
+Installation:
+
+Download the patch from http://www.genashor.com/qmail/ the patch will be named
+qmailDomainChecks_xx.patch, where xx should be replaced by the
+appropriate version number.
+
+Go to the qmail-1.03 source directory and type:
+
+   patch -p1 < [path-to-patch]/qmailDomainChecks_xx.patch
+
+Compile and install as usual.  If it helps cut down your spam, I'd love to
+hear from you.
+
+-----------------------------------------------------------------------------
+Any questions, comments email me: gary at genashor.com
+
+Gary Gendel