/etc/auth/yourdomain.com/passwd
From Free Knowledge Base- The DUCK Project: information for everyone
craig@virtdomain.com:!!encrypted_password:5000:5000:Craig J:/var/vmail/craig@virtdomain.com:/bin/false leslie@virtdomain.com:!!encrypted_password:5000:5000:Leslie S:/var/vmail/leslie@virtdomain.com:/bin/false nicolew@virtdomain.com:!!encrypted_password:5000:5000:Nicole W:/var/vmail/nicolew@virtdomain.com:/bin/false