dovecot-lda quota warning email add BCC

[Admin Beckspaced]

Dear dovecot users,

I have setup doveot with quota warning.
Once a quota wearning is reached a shell script is called which then 
sends an email to the user via dovecot LDA

this is the command in the shell script:

/usr/lib/dovecot/dovecot-lda -d $USER -o "plugin/quota=dict:User 
quota::noenforcing:proxy::quota"

I already have looked in the docs: https://wiki.dovecot.org/LDA

but can't find an option to add a BCC

I would like to receive a copy of the quota warning email so I also get 
notified and know if user mailboxes get filled up.

How could I achieve that?

thanks & greetings
Becki