OBM is a groupware, email, LDAP, Windows PDC, CRM, and project management application. It is mainly used as an Exchange or Notes/Domino groupware and mail server replacement, as an LDAP directory, as a Windows PDC, as a contact and customer database, as a project management tool, or as any combination of these functions. It provides groupware (calendars, contacts, and tasks) connectors for Outlook, Thunderbird/Lightning, and PDAs. It supports internationalization and themes. It is highly scalable, and is used by sites from five to many thousands of users.