Meus manuais, deixe-me mostrar-lhes:
BCC user@domain
Add the specified address as a BCC recipient, and inspect the next input line. The address must have a local part and domain part. The number of BCC addresses that can be added is limited only by the amount of available storage space.
Note 1: the BCC address is added as if it was specified with NOTIFY=NONE. The sender will not be notified when the BCC address is undeliverable, as long as all down-stream software implements RFC 3461.
Note 2: this ignores duplicate addresses (with the same delivery status notification options).
This feature is available in Postfix 3.0 and later.
(ênfase adicionada)