An EMTU must provide for the following capabilities:

(a) Messaging from vessel to shore, and from shore to vessel by authorized entities, must have a minimum supported message length of 1kb.

(b) There must be a confirmation of delivery function that allows a user to ascertain whether a specific message was successfully transmitted to the MCS email server(s).

(c) Notification of failed delivery to the EMTU must be sent to the sender of the message. The failed delivery notification must include sufficient information to identify the specific message that failed and the cause of failure (e.g.; invalid address, EMTU switched off, etc.).

(d) The EMTU must have an automatic retry feature in the event that a message fails to be delivered.

(e) The EMTU user interface must:

(1) Support an “address book” capability and a function permitting a “reply” to a received message without re-entering the sender's address.

(2) Provide the ability to review by date order, or by recipient, messages that were previously sent. The EMTU terminal must support a minimum message history of 50 sent messages—commonly referred to as an “Outbox” or “Sent” message display.

(3) Provide the ability to review by date order, or by sender, all messages received. The EMTU terminal must support a minimum message history of at least 50 messages in an inbox.