diff -urN src.orig/acl.c src/acl.c
--- src.orig/acl.c	Thu Aug 30 17:31:06 2007
+++ src/acl.c	Thu Sep 13 12:33:53 2007
@@ -91,6 +91,7 @@
 #ifdef WITH_CONTENT_SCAN
        ACLC_REGEX,
 #endif
+       ACLC_REMOVE_HEADER,
        ACLC_SENDER_DOMAINS,
        ACLC_SENDERS,
        ACLC_SET,
@@ -153,6 +154,7 @@
 #ifdef WITH_CONTENT_SCAN
   US"regex",
 #endif
+  US"remove_header",
   US"sender_domains", US"senders", US"set",
 #ifdef WITH_CONTENT_SCAN
   US"spam",
@@ -277,6 +279,7 @@
 #ifdef WITH_CONTENT_SCAN
   TRUE,    /* regex */
 #endif
+  TRUE,    /* remove_header */
   FALSE,   /* sender_domains */
   FALSE,   /* senders */
   TRUE,    /* set */
@@ -337,6 +340,7 @@
 #ifdef WITH_CONTENT_SCAN
   FALSE,   /* regex */
 #endif
+  TRUE,    /* remove_header */
   FALSE,   /* sender_domains */
   FALSE,   /* senders */
   TRUE,    /* set */
@@ -497,6 +501,12 @@
     (1<<ACL_WHERE_MIME)),
   #endif
 
+  (unsigned int)
+  ~((1<<ACL_WHERE_MAIL)|(1<<ACL_WHERE_RCPT)|       /* remove_header */
+    (1<<ACL_WHERE_PREDATA)|(1<<ACL_WHERE_DATA)|
+    (1<<ACL_WHERE_MIME)|(1<<ACL_WHERE_NOTSMTP)|
+    (1<<ACL_WHERE_NOTSMTP_START)),
+
   (1<<ACL_WHERE_AUTH)|(1<<ACL_WHERE_CONNECT)|      /* sender_domains */
     (1<<ACL_WHERE_HELO)|
     (1<<ACL_WHERE_MAILAUTH)|(1<<ACL_WHERE_QUIT)|
@@ -1030,6 +1040,20 @@
 
 
 
+static void
+setup_remove_header(uschar *hnames)
+{
+if (*hnames != 0)
+  {
+  if (acl_removed_headers == NULL)
+    acl_removed_headers = hnames;
+  else
+    acl_removed_headers = string_sprintf("%s : %s", acl_removed_headers, hnames);
+  }
+}
+
+
+
 
 /*************************************************
 *               Handle warnings                  *
@@ -3029,6 +3053,10 @@
     break;
     #endif
 
+    case ACLC_REMOVE_HEADER:
+    setup_remove_header(arg);
+    break;
+ 
     case ACLC_SENDER_DOMAINS:
       {
       uschar *sdomain;
diff -urN src.orig/globals.c src/globals.c
--- src.orig/globals.c	Thu Aug 30 17:31:06 2007
+++ src/globals.c	Thu Sep 13 12:34:37 2007
@@ -179,6 +179,7 @@
 #endif
 uschar *acl_not_smtp_start     = NULL;
 
+uschar *acl_removed_headers    = NULL;
 uschar *acl_smtp_auth          = NULL;
 uschar *acl_smtp_connect       = NULL;
 uschar *acl_smtp_data          = NULL;
diff -urN src.orig/globals.h src/globals.h
--- src.orig/globals.h	Thu Aug 30 17:31:06 2007
+++ src/globals.h	Thu Sep 13 12:35:15 2007
@@ -115,6 +115,7 @@
 extern uschar *acl_not_smtp_mime;      /* For MIME parts of ditto */
 #endif
 extern uschar *acl_not_smtp_start;     /* ACL run at the beginning of a non-SMTP session */
+extern uschar *acl_removed_headers;    /* Headers deleted by an ACL */
 extern uschar *acl_smtp_auth;          /* ACL run for AUTH */
 extern uschar *acl_smtp_connect;       /* ACL run on SMTP connection */
 extern uschar *acl_smtp_data;          /* ACL run after DATA received */
diff -urN src.orig/receive.c src/receive.c
--- src.orig/receive.c	Thu Aug 30 17:31:06 2007
+++ src/receive.c	Thu Sep 13 12:35:45 2007
@@ -933,6 +933,41 @@
 {
 header_line *h, *next;
 header_line *last_received = NULL;
+int sep = ':';
+
+if (acl_removed_headers != NULL)
+  {
+  DEBUG(D_receive|D_acl) debug_printf(">>Headers deleted by %s ACL:\n", acl_name);
+
+  for (h = header_list; h != NULL; h = h->next)
+    {
+    int i;
+    uschar *list;
+    BOOL include_header;
+
+    if (h->type == htype_old) continue;
+
+    include_header = TRUE;
+    list = acl_removed_headers;
+
+    int sep = ':';         /* This is specified as a colon-separated list */
+    uschar *s;
+    uschar buffer[128];
+    while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
+            != NULL)
+      {
+      int len = Ustrlen(s);
+      if (header_testname(h, s, len, FALSE))
+	{
+	h->type = htype_old;
+        DEBUG(D_receive|D_acl) debug_printf("  %s", h->text);
+	}
+      }
+    }
+
+  acl_removed_headers = NULL;
+  DEBUG(D_receive|D_acl) debug_printf(">>\n");
+  }
 
 if (acl_added_headers == NULL) return;
 DEBUG(D_receive|D_acl) debug_printf(">>Headers added by %s ACL:\n", acl_name);
diff -urN src.orig/smtp_in.c src/smtp_in.c
--- src.orig/smtp_in.c	Thu Aug 30 17:31:06 2007
+++ src/smtp_in.c	Thu Sep 13 12:36:05 2007
@@ -996,6 +996,7 @@
 message_linecount = 0;
 message_size = -1;
 acl_added_headers = NULL;
+acl_removed_headers = NULL;
 queue_only_policy = FALSE;
 rcpt_smtp_response = NULL;
 rcpt_smtp_response_same = TRUE;