diff -urN src.orig/spool_mbox.c src/spool_mbox.c
--- src.orig/spool_mbox.c	Thu Sep  9 18:43:10 2004
+++ src/spool_mbox.c	Thu Sep  9 18:43:24 2004
@@ -38,6 +38,9 @@
   uschar *received;
   uschar *timestamp;
   */
+  uschar *mbox_delimiter;
+  uschar *envelope_from;
+  uschar *envelope_to;
   
   if (!spool_mbox_ok) {
     /* create scan directory, if not present */
@@ -60,6 +63,47 @@
     if (mbox_file == NULL) {
       debug_printf("unable to open file for writing: %s\n", mbox_path);
       return NULL;
+    };
+
+    /* Generate mailbox delimiter */
+    mbox_delimiter = expand_string(US"From ${sender_address} ${tod_bsdinbox}\n");
+    if (mbox_delimiter != NULL) {
+      if (mbox_delimiter[0] != 0) {
+        i = fwrite(mbox_delimiter, 1, Ustrlen(mbox_delimiter), mbox_file);
+        if (i != Ustrlen(mbox_delimiter)) {
+          debug_printf("error/short write on writing in: %s", mbox_path);
+          fclose(mbox_file);
+          return NULL;
+        };
+      };
+    };
+    /* Generate X-Envelope-From header */
+    envelope_from = expand_string(US"${sender_address}");
+    if (envelope_from != NULL) {
+      if (envelope_from[0] != 0) {
+        uschar *my_envelope_from;
+        my_envelope_from = string_sprintf("X-Envelope-From: <%s>\n", envelope_from);
+        i = fwrite(my_envelope_from, 1, Ustrlen(my_envelope_from), mbox_file);
+        if (i != Ustrlen(my_envelope_from)) {
+          debug_printf("error/short write on writing in: %s", mbox_path);
+          fclose(mbox_file);
+          return NULL;
+        };
+      };
+    };
+    /* Generate X-Envelope-To header */
+    envelope_to = expand_string(US"${if def:received_for{$received_for}}");
+    if (envelope_to != NULL) {
+      if (envelope_to[0] != 0) {
+        uschar *my_envelope_to;
+        my_envelope_to = string_sprintf("X-Envelope-To: <%s>\n", envelope_to);
+        i = fwrite(my_envelope_to, 1, Ustrlen(my_envelope_to), mbox_file);
+        if (i != Ustrlen(my_envelope_to)) {
+          debug_printf("error/short write on writing in: %s", mbox_path);
+          fclose(mbox_file);
+          return NULL;
+        };
+      };
     };
     
     /* Generate a preliminary Received: header and put it in the file.