--- sendmail-8.13.3/sendmail/collect.c~	2004-12-01 00:29:15.000000000 +0100
+++ sendmail-8.13.3/sendmail/collect.c	2005-03-08 09:43:40.848804648 +0100
@@ -15,6 +15,8 @@
 
 SM_RCSID("@(#)$Id$")
 
+#define MAXHDRZ 512
+
 static void	collecttimeout __P((int));
 static void	eatfrom __P((char *volatile, ENVELOPE *));
 static void	collect_doheader __P((ENVELOPE *));
@@ -288,6 +290,7 @@
 	register ENVELOPE *e;
 	bool rsetsize;
 {
+	int hdrz = 0;
 	register SM_FILE_T *volatile df;
 	volatile bool ignrdot;
 	volatile int dbto;
@@ -613,6 +616,16 @@
 				mstate = MS_BODY;
 				goto nextstate;
 			}
+ 
+            if (hdrz++>MAXHDRZ)
+                        {
+                                sm_syslog(LOG_NOTICE, e->e_id,
+                                "excessive headers from %s during message collect",
+                                CurHostName ? CurHostName : "<local machine>");
+                                errno = 0;
+                                usrerr("451 Stop this. You are lame.");
+                                goto readerr;
+                        }
 
 			/* check for possible continuation line */
 			do