On some systems users have direct (login) access to the mail server computer, and some of them get used to Local Mailers - mail, elm, and others. Local Mailers do not use any network protocol to access mailboxes. Instead, those programs read and modify mailbox files directly, via the file system.
The CommuniGate Pro allows you to create Accounts with Legacy INBOX Mailboxes. These Mailboxes are stored not inside the CommuniGate Pro base directory, but in the system directory known to the legacy mailer applications.
Since these INBOX files can be read and modified directly, bypassing the CommuniGate Pro protocols and modules, the Server needs to synchronize its activity with legacy mail applications using OS file locking features - either FileLevel locks or FileRange locks.
On Unix systems the FileLevel locks are known as flock operations, and RangeLevel locks are known as fcntl operations. Check with your OS manual to see which method the legacy mailers use on your system, and configure the CommuniGate Pro Server to use that method. For systems that support only one file locking mechanism (MS Windows, Sun Solaris, and some other systems), selecting either method selects that mechanism.
You should use Legacy Mailboxes only when absolutely necessary, because:
If you have to support Local Mailer compatibility for all or some Accounts in a Domain (usually - in the Main Domain), you should specify the Legacy INBOX settings for that Domain.
When you create an Account that has an Legacy INBOX, the Server checks if the Account INBOX file already exists in the specified location and creates one if the Mailbox file is absent.
When you delete an Account that has an Legacy INBOX, the Server does NOT remove the INBOX Mailbox file.