Before the Custom BCC for Program Emails feature is enabled, the program email configuration appears as follows.

You could configure a global bcc address in Settings that would apply to all programs. With the Custom BCC for Program Emails feature, you can override the global setting at the program level.

If you leave the box blank at the program level, the global bcc address will be used. If you enter one or more bcc addresses at the program level, the global address will not be in effect for this program - only the addresses specified for the program will be used.

However, if you want to use the global bcc address and one or more other addresses for a program, include the global bcc address in your list for the program.

To enable the Custom BCC for Program Emails go to Settings > Email > Custom BCC for Program Emails. 

After the Custom BCC for Program Emails feature is enabled, the program email configuration now appears as follows. If you leave the bcc box blank, the global bcc address will be used.

You can override the global bcc configuration by entering one or more email addresses in the bcc box for this program.