On your Mac's Mail.app, you can freely give yourself a BCC address when sending

In Mail.app on Mac, you can freely set your own BCC address when sending
Let me introduce you.
Basically, Mail.app is not configurable.
in the terminal.
defaults read com.apple.mail UserHeaders
After setting the above, enter the email address you want to set to Bcc.
defaults write com.apple.mail UserHeaders' {"Bcc" = "Enter email address here";} '
You're all set.