diff --git a/src/lib-index/mail-index-private.h b/src/lib-index/mail-index-private.h
index d280b46a7d..494da0f912 100644
--- a/src/lib-index/mail-index-private.h
+++ b/src/lib-index/mail-index-private.h
@@ -45,9 +45,6 @@ struct mail_index_sync_map_ctx;
 typedef int mail_index_expunge_handler_t(struct mail_index_sync_map_ctx *ctx,
 					 uint32_t seq, const void *data,
 					 void **sync_context, void *context);
-typedef int mail_index_sync_handler_t(struct mail_index_sync_map_ctx *ctx,
-				      uint32_t seq, void *old_data,
-				      const void *new_data, void **context);
 typedef void mail_index_sync_lost_handler_t(struct mail_index *index);
 
 #define MAIL_INDEX_HEADER_SIZE_ALIGN(size) \
@@ -93,11 +90,6 @@ enum mail_index_sync_handler_type {
 	MAIL_INDEX_SYNC_HANDLER_VIEW	= 0x04
 };
 
-struct mail_index_sync_handler {
-	mail_index_sync_handler_t *callback;
-        enum mail_index_sync_handler_type type;
-};
-
 struct mail_index_registered_ext {
 	const char *name;
 	uint32_t index_idx; /* index ext_id */
@@ -105,7 +97,6 @@ struct mail_index_registered_ext {
 	uint16_t record_size;
 	uint16_t record_align;
 
-	struct mail_index_sync_handler sync_handler;
 	mail_index_expunge_handler_t *expunge_handler;
 
 	void *expunge_context;
@@ -242,11 +233,6 @@ void mail_index_register_expunge_handler(struct mail_index *index,
 					 void *context);
 void mail_index_unregister_expunge_handler(struct mail_index *index,
 					   uint32_t ext_id);
-void mail_index_register_sync_handler(struct mail_index *index, uint32_t ext_id,
-				      mail_index_sync_handler_t *cb,
-				      enum mail_index_sync_handler_type type);
-void mail_index_unregister_sync_handler(struct mail_index *index,
-					uint32_t ext_id);
 void mail_index_register_sync_lost_handler(struct mail_index *index,
 					   mail_index_sync_lost_handler_t *cb);
 void mail_index_unregister_sync_lost_handler(struct mail_index *index,
diff --git a/src/lib-index/mail-index-sync-ext.c b/src/lib-index/mail-index-sync-ext.c
index 66c6c08ae4..b8cc62e7e5 100644
--- a/src/lib-index/mail-index-sync-ext.c
+++ b/src/lib-index/mail-index-sync-ext.c
@@ -94,26 +94,8 @@ void mail_index_sync_init_handlers(struct mail_index_sync_map_ctx *ctx)
 
 void mail_index_sync_deinit_handlers(struct mail_index_sync_map_ctx *ctx)
 {
-	const struct mail_index_registered_ext *rext;
-	void **extra_contexts;
-	unsigned int i, rext_count, context_count;
-
-	if (!array_is_created(&ctx->extra_contexts))
-		return;
-
-	rext = array_get(&ctx->view->index->extensions, &rext_count);
-	extra_contexts =
-		array_get_modifiable(&ctx->extra_contexts, &context_count);
-	i_assert(context_count <= rext_count);
-
-	for (i = 0; i < context_count; i++) {
-		if (extra_contexts[i] != NULL) {
-			rext[i].sync_handler.callback(ctx, 0, NULL, NULL,
-						      &extra_contexts[i]);
-		}
-	}
-
-	array_free(&ctx->extra_contexts);
+	if (array_is_created(&ctx->extra_contexts))
+		array_free(&ctx->extra_contexts);
 }
 
 static struct mail_index_ext_header *
@@ -660,10 +642,8 @@ mail_index_sync_ext_rec_update(struct mail_index_sync_map_ctx *ctx,
 	struct mail_index_view *view = ctx->view;
 	struct mail_index_record *rec;
 	const struct mail_index_ext *ext;
-	const struct mail_index_registered_ext *rext;
 	void *old_data;
 	uint32_t seq;
-	int ret;
 
 	i_assert(ctx->cur_ext_map_idx != (uint32_t)-1);
 	i_assert(!ctx->cur_ext_ignore);
@@ -684,20 +664,6 @@ mail_index_sync_ext_rec_update(struct mail_index_sync_map_ctx *ctx,
 	rec = MAIL_INDEX_REC_AT_SEQ(view->map, seq);
 	old_data = PTR_OFFSET(rec, ext->record_offset);
 
-	rext = array_idx(&view->index->extensions, ext->index_idx);
-
-	/* call sync handlers only when its registered type matches with
-	   current synchronization type (index/view) */
-	if ((rext->sync_handler.type & ctx->type) != 0) {
-		void **extra_context =
-			array_idx_modifiable(&ctx->extra_contexts,
-					     ext->index_idx);
-		ret = rext->sync_handler.callback(ctx, seq, old_data, u + 1,
-						  extra_context);
-		if (ret <= 0)
-			return ret;
-	}
-
 	/* @UNSAFE */
 	memcpy(old_data, u + 1, ctx->cur_ext_record_size);
 	if (ctx->cur_ext_record_size < ext->record_size) {
diff --git a/src/lib-index/mail-index.c b/src/lib-index/mail-index.c
index 0cc024339a..ea7979a9a7 100644
--- a/src/lib-index/mail-index.c
+++ b/src/lib-index/mail-index.c
@@ -315,31 +315,6 @@ void mail_index_unregister_expunge_handler(struct mail_index *index,
 	rext->expunge_handler = NULL;
 }
 
-void mail_index_register_sync_handler(struct mail_index *index, uint32_t ext_id,
-				      mail_index_sync_handler_t *cb,
-				      enum mail_index_sync_handler_type type)
-{
-	struct mail_index_registered_ext *rext;
-
-	rext = array_idx_modifiable(&index->extensions, ext_id);
-	i_assert(rext->sync_handler.callback == NULL);
-
-	rext->sync_handler.callback = cb;
-	rext->sync_handler.type = type;
-}
-
-void mail_index_unregister_sync_handler(struct mail_index *index,
-					uint32_t ext_id)
-{
-	struct mail_index_registered_ext *rext;
-
-	rext = array_idx_modifiable(&index->extensions, ext_id);
-	i_assert(rext->sync_handler.callback != NULL);
-
-	rext->sync_handler.callback = NULL;
-	rext->sync_handler.type = 0;
-}
-
 void mail_index_register_sync_lost_handler(struct mail_index *index,
 					   mail_index_sync_lost_handler_t *cb)
 {