An organisation's network architecture requires that employees can access their emails from both their office desktop computers and their remote mobile devices. It is vital that when an email is read, marked as flagged, or deleted on one device, the change is reflected across all other devices in real-time. Additionally, the system must allow the client devices to transmit outbound emails to the local mail server to be relayed to external domains.

Which pair of protocols must be implemented to support the synchronised retrieval of emails and the outbound transmission of emails respectively?