Quota configuration of Dovecot

Discuss

Hello,
I was surprised that the disk usage information given by the webadmin was not the same that the the space given by du -h /var/mail.
I realized that Dovecot is configured so that the Trash and SPAM are not taken in account in the mail quota:

Do you know why this choice?
Would you also prefer that Trash and SPAM be taken in account by the mail quota?