--- a/src/lib-storage/mail-storage.h	Fri May 06 00:29:16 2016 +0300
+++ b/src/lib-storage/mail-storage.h	Fri May 27 22:15:07 2016 +0300
@@ -49,7 +49,13 @@
 	/* Force opening mailbox and ignoring any ACLs */
 	MAILBOX_FLAG_IGNORE_ACLS	= 0x100,
 	/* Open mailbox even if it's already marked as deleted */
-	MAILBOX_FLAG_OPEN_DELETED	= 0x200
+	MAILBOX_FLAG_OPEN_DELETED	= 0x200,
+	/* Mailbox is opened for deletion, which should be performed as
+	   efficiently as possible, even allowing the mailbox state to become
+	   inconsistent. For example this disables lazy_expunge plugin and
+	   quota updates (possibly resulting in broken quota). and This is
+	   useful for example when deleting entire user accounts. */
+	MAILBOX_FLAG_DELETE_UNSAFE	= 0x400
 };
 
 enum mailbox_feature {

--- a/src/plugins/lazy-expunge/lazy-expunge-plugin.c	Fri May 06 00:29:16 2016 +0300
+++ b/src/plugins/lazy-expunge/lazy-expunge-plugin.c	Fri May 27 22:15:07 2016 +0300
@@ -448,7 +448,7 @@
 	union mailbox_module_context *mbox;
 	struct mailbox_vfuncs *v = box->vlast;
 
-	if (llist == NULL)
+	if (llist == NULL || (box->flags & MAILBOX_FLAG_DELETE_UNSAFE) != 0)
 		return;
 
 	mbox = p_new(box->pool, union mailbox_module_context, 1);

--- a/src/plugins/quota/quota-storage.c	Fri May 06 00:29:16 2016 +0300
+++ b/src/plugins/quota/quota-storage.c	Fri May 27 22:15:07 2016 +0300
@@ -328,7 +328,8 @@
 	if (qbox->module_ctx.super.sync_notify != NULL)
 		qbox->module_ctx.super.sync_notify(box, uid, sync_type);
 
-	if (sync_type != MAILBOX_SYNC_TYPE_EXPUNGE || qbox->recalculate) {
+	if (sync_type != MAILBOX_SYNC_TYPE_EXPUNGE || qbox->recalculate ||
+	    (box->flags & MAILBOX_FLAG_DELETE_UNSAFE) != 0) {
 		if (uid == 0) {
 			/* free the transaction before view syncing begins,
 			   otherwise it'll crash. */