--- src/smtp_in.c.orig	2003-12-13 11:34:50.000000000 +0000
+++ src/smtp_in.c	2003-12-13 12:08:56.000000000 +0000
@@ -194,6 +194,12 @@
 static int     smtp_had_eof;
 static int     smtp_had_error;
 
+/* The following variables get used to make sure that we don't give out protocol
+errors to data which the client couldn't have known failed based on it choosing
+to pipeline them.*/
+static BOOL smtp_pkt_boundary = TRUE;
+static int  smtp_pkt_mail_count = 0;
+static int  smtp_pkt_rcpt_count = 0;
 
 /*************************************************
 *          SMTP version of getc()                *
@@ -502,6 +508,19 @@
 
 if (hadnull) return BADCHAR_CMD;
 
+/* If we set a boundary last time, then reset our counters for what's in
+this pipelining packet.*/
+
+if(smtp_pkt_boundary==TRUE) {
+    smtp_pkt_boundary=FALSE;
+    smtp_pkt_mail_count=0;
+    smtp_pkt_rcpt_count=0;
+}
+
+if(smtp_inptr == smtp_inend) {
+    smtp_pkt_boundary=TRUE;
+}
+
 /* Scan command list and return identity, having set the data pointer
 to the start of the actual data characters. Check for SMTP synchronization
 if required. */
@@ -2479,6 +2498,7 @@
     it is the canonical extracted address which is all that is kept. */
 
     case MAIL_CMD:
+    smtp_pkt_mail_count++;             /* Count to keep track of client pipeline */
     smtp_mailcmd_count++;              /* Count for limit and ratelimit */
 
     if (helo_required && !helo_seen)
@@ -2765,14 +2785,24 @@
     extracted address. */
 
     case RCPT_CMD:
+    smtp_pkt_rcpt_count++;     /* keep track of client pipelining */
     rcpt_count++;
 
     if (sender_address == NULL)
       {
-      done = synprot_error(L_smtp_protocol_error, 503, NULL,
-        US"sender not yet given");
-      rcpt_fail_count++;
-      break;
+      if(smtp_pkt_mail_count)
+	{
+        smtp_printf("503 sender not yet given\r\n");
+        rcpt_fail_count++;
+        break;
+	}
+      else
+	{
+        done = synprot_error(L_smtp_protocol_error, 503, NULL,
+          US"sender not yet given");
+        rcpt_fail_count++;
+        break;
+	}
       }
 
     if (smtp_data[0] == 0)
@@ -2918,21 +2948,39 @@
 
     /* The DATA command is legal only if it follows successful MAIL FROM
     and RCPT TO commands. This function is complete when a valid DATA
-    command is encountered. */
+    command is encountered. However, we must make sure that we don't
+    penalise clients that can't tell that previous commands failed because
+    they pipelined everything. */
 
     case DATA_CMD:
     if (sender_address == NULL)
       {
-      done = synprot_error(L_smtp_protocol_error, 503, NULL,
-        US"MAIL command must precede DATA");
-      break;
+      if(smtp_pkt_mail_count)
+	{
+        smtp_printf("554 No valid senders\r\n");
+        break;
+	}
+      else
+	{
+        done = synprot_error(L_smtp_protocol_error, 503, NULL,
+          US"MAIL command must precede DATA");
+        break;
+	}
       }
 
     if (!discarded && recipients_count <= 0)
       {
-      done = synprot_error(L_smtp_protocol_error, 503, NULL,
-        US"valid RCPT command must precede DATA");
-      break;
+      if(smtp_pkt_rcpt_count)
+	{
+        smtp_printf("554 No valid recipients\r\n");
+        break;
+	}
+      else
+	{
+        done = synprot_error(L_smtp_protocol_error, 503, NULL,
+          US"valid RCPT command must precede DATA");
+        break;
+	}
       }
 
     if (toomany && recipients_max_reject)