--- itip-formatter.c.orig	2009-07-29 07:38:03.000000000 +0200
+++ itip-formatter.c	2010-04-22 22:23:04.000000000 +0200
@@ -615,6 +615,10 @@
 		goto cleanup;
 	}
 
+    GError **error ;
+    gboolean read_only ;
+    if (e_cal_is_read_only(ecal, &read_only, error) && read_only) goto cleanup;
+
 	/* Check for conflicts */
 	/* If the query fails, we'll just ignore it */
 	/* FIXME What happens for recurring conflicts? */
