Use domain database MTA option

Alias and address MTA options:  (0 or 1)
The  MTA  option controls whether or not the MTA makes use of the domain database as a source of rewrite rules. In Messaging Server 7.2 and earlier, the default was 1, which means that the MTA would check the database if it existed; as of Messaging Server 7.3, the default is 0, which disables consultation of the domain database.

See also:
 * Domain database
 * Alias and address MTA options
 * Database MTA options