Public Folders (PFs), first introduced in Exchange 4.0, were initially designed as a method of collecting, organizing, and easily sharing information with other users. These days, they are still widely used to share e-mails, contacts, and documents. Users are also able to send e-mails to PFs when these are mail-enabled, allowing PFs to act as a discussion forum or distribution group archive.
Up until Exchange 2013, PFs always had their own dedicated database which could be replicated between servers to achieve resilience and high availability. This also allowed for PFs (or a replica) to be, from a network perspective, closer to users, improving performance and saving bandwidth. One of the biggest headaches with PFs has always been this replication method, with users having to wait several minutes for their PFs to update, among other issues.
PFs take full advantage of the high availability technology of the mailbox store. Specially designed mailboxes are used...