The default format for CommuniGate Pro Mailboxes is the BSD-type text mailbox format: a Mailbox is a text file with messages separated with an empty line and a line starting with the symbols From .
Since most legacy mail systems use this format, the existing mailbox files can be used when migrating to CommuniGate Pro. You should either copy the old mailbox files into the proper places in the CommuniGate Pro Account directories, or you can specify that some Accounts have Legacy INBOXes (see above), and the old mailbox files will be used "in place".
Note: when CommuniGate Pro stores a message in a BSD-type Mailbox, it adds additional fields to the separator (From) line. These fields are ignored by legacy mailers and mail servers, but they allow the CommuniGate Pro Server to keep the message status and unique message ID information. When you make your CommuniGate Pro Server use a BSD-type mailbox file composed with an old mail system, it issues warnings (Log records) about missing fields in the message separators. The Server still opens such mailboxes: it creates empty status flag sets for such messages, and it generates unique IDs on-fly. As users read, move, and/or delete old mail from their mailboxes, messages stored with the old mail system disappear, and the Server stops complaining when opening these mailbox files.