GFI MailSecurity uses 3 ways to count and retrieve users: - Exchange mailboxes, Active Directory, and an internal user database system.

Exchange mailboxes
When GFI MailSecurity is installed on the same machine as Exchange 2000/2003, you can install GFI MailSecurity 8.1 for Exchange 2000/2003 or GFI MailSecurity for Exchange/SMTP 9.0. In both cases, MailSecurity will only read and count users having an Exchange mailbox on the Exchange server where MailSecurity is installed.

Note: Public Folders are not retrieved and counted by MailSecurity

Active Directory
When GFI MailSecurity for Exchange/SMTP 9.0 is not installed on the same machine as your mail server and Active Directory is present, Active Directory is used. GFI MailSecurity for Exchange/SMTP 9.0 will only retrieve mail-enabled users and can only retrieve these from the Active Directory domain of which the machine where GFI MailSecurity for Exchange/SMTP 9.0 is installed forms part.

Active Directory is queried using the LDAP protocol.

Note: The System mailbox is not counted by MailSecurity

Internal user database system
An internal user database system is used in all the other situations. Therefore, if the users are being synchronized from Exchange 5.5, the synchronization process will synchronize the Exchange 5.5 mailboxes with the internal user database system in GFI MailSecurity for Exchange/SMTP 9.0 .

This internal user database system will also be used when GFI MailSecurity for Exchange/SMTP 9.0 is installed on a separate machine then the mail server, and Active Directory is not used. In this case, the users can either be entered manually, or saved automatically from the FROM email address of outbound emails. All the users stored in this internal user database system can be used for user-based content filtering.