Create a site, say "testsite.com". Under that site, create a mailuser say "firstname.lastname@example.org" tied to system account say "web1_myuser". Delete that mailuser (via ISPConfig's web interface). The deletion seems incomplete. Both ISPConfig's own DB (table isp_isp_user) and the system's passwd file still show the mailuser (and the corresponding system user). In effect, it seems that creating a system user (invariably necessary to create a mailuser in ISPConfig) PERMANENTLY prevents the login ID from being reused, even if we try deleting the user from ISPConfig. Of course, I can "clean up" the records in ISPConfig's DB manually, and do a system `userdel' as well. But that puts ISPConfig far from being a self-contained control panel. My boss is not a Linux expert. Please advice? Thanks.