Bccserver, nobccserver Channel Options

XBCC SMTP Extension Support
The  channel option, when placed on a SUBMIT server channel, enables the XBCC extension. This extension adds a single XBCC argument to the RCPT TO command. When present, it marks the corresponding recipient as a blind carbon recipient and the MTA will generate a separate message copy to this recipient and add a Bcc: header field to the copy.

The XBCC argument value may optionally be used to specify a phrase which will preceed the recipient address in the Bcc: header field.

The  channel option disables this extension and is the default.