Extension:Echo/echo email batch table

Schema
mysql> describe echo_email_batch; ++-+--+-+-++ ++-+--+-+-++ ++-+--+-+-++ 5 rows in set (0.00 sec)
 * Field             | Type                | Null | Key | Default | Extra          |
 * eeb_id            | int(10) unsigned    | NO   | PRI | NULL    | auto_increment |
 * eeb_user_id       | int(10) unsigned    | NO   | MUL | NULL    |                |
 * eeb_event_priority | tinyint(3) unsigned | NO  |     | 10      |                |
 * eeb_event_id      | int(10) unsigned    | NO   |     | NULL    |                |
 * eeb_event_hash    | varbinary(32)       | NO   |     | NULL    |                |