You can forward these messages to our mailcow spam trap, too. 🙂
Just use an alias, not bcc. Bcc is not meant to be used like this.
If you want to forward mails to one or more destinations and keep them in your local mailbox, too, you need to create a filter in /mailbox.
If you want to send a copy to mailcows spam trap, mail me to firstname.lastname@example.org, please.