diff -burp qmail-1.03.orig/qmail-smtpd.c qmail-1.03.logging/qmail-smtpd.c
--- qmail-1.03.orig/qmail-smtpd.c	2003-09-11 20:31:52.000000000 -0500
+++ qmail-1.03.logging/qmail-smtpd.c	2010-01-05 18:02:43.000000000 -0600
@@ -38,16 +38,20 @@ int safewrite(fd,buf,len) int fd; char *
 
 char ssoutbuf[512];
 substdio ssout = SUBSTDIO_FDBUF(safewrite,1,ssoutbuf,sizeof ssoutbuf);
+char sserrbuf[512];
+substdio sserr = SUBSTDIO_FDBUF(write,2,sserrbuf,sizeof sserrbuf);
 
+void logit(const char* message);
+void logit2(const char* message, const char* reason);
 void flush() { substdio_flush(&ssout); }
 void out(s) char *s; { substdio_puts(&ssout,s); }
 
-void die_read() { _exit(1); }
-void die_alarm() { out("451 timeout (#4.4.2)\r\n"); flush(); _exit(1); }
+void die_read() { logit("read failed"); _exit(1); }
+void die_alarm() { logit("timeout"); out("451 timeout (#4.4.2)\r\n"); flush(); _exit(1); }
 void die_nomem() { out("421 out of memory (#4.3.0)\r\n"); flush(); _exit(1); }
-void die_control() { out("421 unable to read controls (#4.3.0)\r\n"); flush(); _exit(1); }
-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 die_control() { logit("unable to read controls"); out("421 unable to read controls (#4.3.0)\r\n"); flush(); _exit(1); }
+void die_ipme() { logit("unable to figure out my IP addresses"); out("421 unable to figure out my IP addresses (#4.3.0)\r\n"); flush(); _exit(1); }
+void straynewline() { logit("bad newlines"); 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"); }
@@ -221,6 +225,61 @@ int seenmail = 0;
 int flagbarf; /* defined if seenmail */
 stralloc mailfrom = {0};
 stralloc rcptto = {0};
+stralloc log_buf = {0};
+
+void logit(message) const char* message;
+{
+  if (!stralloc_copys(&log_buf, "qmail-smtpd: ")) die_nomem();
+  if (!stralloc_cats(&log_buf, message)) die_nomem();
+  if (!stralloc_catb(&log_buf, ": ", 2)) die_nomem();
+  if (mailfrom.s) {
+      if (!stralloc_catb(&log_buf, mailfrom.s, mailfrom.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_catb(&log_buf, " from ", 6)) die_nomem();
+  if (!stralloc_cats(&log_buf, remoteip)) die_nomem();
+  if (!stralloc_catb(&log_buf, " to ", 4)) die_nomem();
+  if (addr.s) {
+      if (!stralloc_catb(&log_buf, addr.s, addr.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_catb(&log_buf, " helo ", 6)) die_nomem();
+  if (helohost.s) {
+      if (!stralloc_catb(&log_buf, helohost.s, helohost.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_catb(&log_buf, "\n", 1)) die_nomem();
+  substdio_putflush(&sserr, log_buf);
+}
+
+void logit2(message, reason)
+const char* message;
+const char* reason;
+{
+  if (!stralloc_copys(&log_buf,"qmail-smtpd: ")) die_nomem();
+  if (!stralloc_cats(&log_buf, message)) die_nomem();
+  if (!stralloc_cats(&log_buf, " (")) die_nomem();
+  if (!stralloc_cats(&log_buf, reason)) die_nomem();
+  if (!stralloc_cats(&log_buf, "): ")) die_nomem();
+  if (mailfrom.s) {
+      if (!stralloc_catb(&log_buf, mailfrom.s, mailfrom.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_cats(&log_buf," from ")) die_nomem();
+  if (!stralloc_cats(&log_buf, remoteip)) die_nomem();
+  if (!stralloc_cats(&log_buf, " to ")) die_nomem();
+  if (addr.s) {
+      if (!stralloc_catb(&log_buf, addr.s, addr.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_cats(&log_buf, " helo ")) die_nomem();
+  if (helohost.s) {
+      if (!stralloc_catb(&log_buf, helohost.s, helohost.len-1)) die_nomem();
+  } else
+      if (!stralloc_catb(&log_buf, "(null)", 6)) die_nomem();
+  if (!stralloc_catb(&log_buf, "\n", 1)) die_nomem();
+  substdio_putflush(&sserr, log_buf);
+}
 
 void smtp_helo(arg) char *arg;
 {
@@ -250,7 +309,7 @@ void smtp_mail(arg) char *arg;
 void smtp_rcpt(arg) char *arg; {
   if (!seenmail) { err_wantmail(); return; }
   if (!addrparse(arg)) { err_syntax(); return; }
-  if (flagbarf) { err_bmf(); return; }
+  if (flagbarf) { logit("badmailfrom"); err_bmf(); return; }
   if (relayclient) {
     --addr.len;
     if (!stralloc_cats(&addr,relayclient)) die_nomem();
@@ -386,10 +445,24 @@ void smtp_data() {
   qmail_put(&qqt,rcptto.s,rcptto.len);
  
   qqx = qmail_close(&qqt);
-  if (!*qqx) { acceptmessage(qp); return; }
-  if (hops) { out("554 too many hops, this message is looping (#5.4.6)\r\n"); return; }
-  if (databytes) if (!bytestooverflow) { out("552 sorry, that message size exceeds my databytes limit (#5.3.4)\r\n"); return; }
-  if (*qqx == 'D') out("554 "); else out("451 ");
+  if (!*qqx) { acceptmessage(qp); logit("message accepted"); return; }
+  if (hops) {
+    out("554 too many hops, this message is looping (#5.4.6)\r\n");
+    logit("message looping");
+    return;
+  }
+  if (databytes) if (!bytestooverflow) {
+    out("552 sorry, that message size exceeds my databytes limit (#5.3.4)\r\n");
+    logit("message too big");
+    return;
+  }
+  if (*qqx == 'D') {
+    out("554 ");
+    logit2("message rejected", qqx + 1);
+  } else {
+    out("451 ");
+    logit2("message delayed", qqx + 1);
+  }
   out(qqx + 1);
   out("\r\n");
 }