Use precedence MTA option

Notification message MTA options:  (0 or 1)
The  MTA option controls whether or not the MTA makes use of the information contained in Precedence: header lines when deciding whether to send a delayed delivery notification message. With  set to , the default, such warning  messages are not sent for messages with precedence " " or " ". To instead have the MTA   ignore the Precedence: header line, set   to.

See also:
 * Processing priority MTA options
 * Notification message MTA options