--- vacation.c.orig	2006-09-12 11:24:50.000000000 +0300
+++ vacation.c.patched	2006-10-03 17:18:47.233459022 +0300
@@ -399,8 +399,8 @@
 {
   mu_sieve_value_t *arg;
   char *value;
-  char *subject;
-  int subject_allocated;
+  char *subject = NULL;
+  int subject_allocated = 0;
   mu_header_t hdr;
   
   if (mu_sieve_tag_lookup (tags, "subject", &arg))
@@ -449,6 +449,9 @@
       free (value);
     }
 
+  if (subject == NULL) /* The original message had no subject or its subject was empty */
+    subject = "Re: Your mail";
+
   if (mu_rfc2047_encode (MU_SIEVE_CHARSET, "quoted-printable",
 			 subject, &value))
     mu_header_set_value (newhdr, MU_HEADER_SUBJECT, subject, 0);