CREATE TABLE `virtual_aliases` (
  `alias` varchar(100) NOT NULL,
  `mailbox` varchar(100) NOT NULL,
  `created_at` datetime DEFAULT NULL,
  `expire_at` datetime DEFAULT NULL,
  `enabled` int(1) DEFAULT '1',
  UNIQUE KEY `unique_alias` (`alias`),
  KEY `mailbox_alias` (`alias`),
  KEY `mailbox_expire_at` (`expire_at`)
)