Remember to restart DirectAdmin after you have saved those config file changes:
/etc/init.d/directadmin restart
---
skip_databases_in_backups=1: This will exclude all MySQL databases during the backup process. skip_domains_in_backups=1: This will exclude all domains (website files) during the backup process. skip_imap_in_backups=1: This will exclude all email messages which are stored in user mailboxes during the backup process.
You can use =0 if you want to include those items.