--- a/src/lib-storage/index/index-storage.c	Tue Dec 27 15:03:51 2016 -0500
+++ b/src/lib-storage/index/index-storage.c	Wed Dec 28 22:45:22 2016 +0200
@@ -299,6 +299,10 @@
 	box->box_name_hdr_ext_id =
 		mail_index_ext_register(box->index, "box-name", 0, 0, 0);
 
+	box->box_last_rename_stamp_ext_id =
+		mail_index_ext_register(box->index, "last-rename-stamp",
+					sizeof(uint32_t), 0, sizeof(uint32_t));
+
 	box->opened = TRUE;
 
 	if ((box->enabled_features & MAILBOX_FEATURE_CONDSTORE) != 0)
@@ -794,6 +798,19 @@
 		return -1;
 	}
 
+	if (mailbox_open(dest) == 0) {
+		struct mail_index_transaction *t =
+			mail_index_transaction_begin(dest->view, 0);
+
+		uint32_t stamp = ioloop_time;
+
+		mail_index_update_header_ext(t, dest->box_last_rename_stamp_ext_id,
+					     0, &stamp, sizeof(stamp));
+
+		/* can't do much if this fails anyways */
+		(void)mail_index_transaction_commit(&t);
+	}
+
 	/* we'll track mailbox names, instead of GUIDs. We may be renaming a
 	   non-selectable mailbox (directory), which doesn't even have a GUID */
 	mailbox_name_get_sha128(dest->vname, guid);

--- a/src/lib-storage/mail-storage-private.h	Tue Dec 27 15:03:51 2016 -0500
+++ b/src/lib-storage/mail-storage-private.h	Wed Dec 28 22:45:22 2016 +0200
@@ -361,6 +361,7 @@
 	uint32_t vsize_hdr_ext_id;
 	uint32_t pop3_uidl_hdr_ext_id;
 	uint32_t box_name_hdr_ext_id;
+	uint32_t box_last_rename_stamp_ext_id;
 
 	/* MAIL_RECENT flags handling */
 	ARRAY_TYPE(seq_range) recent_flags;