A shared mailbox is a collaborative mailbox, commonly in Microsoft 365 or Exchange, that multiple authorized users access to send, receive, and manage email from a common address without individual credentials. It can include a shared address book and calendar, centralizing departmental or project contacts. sync.blue® synchronizes shared mailbox contacts with CRMs, PBXs, mobile devices, and other cloud apps through automated two-way updates, keeping the corporate directory consistent and up to date across systems.