Send conversation style. Untiy 4.2(1) introduced the ability to choose the standard or "streamlined" send conversation on a per user basis.
Address messages to other subscribers by. You can select “First Name”, “Last Name” or “ID” in this drop down list. Subscribers address messages over the phone by entering recipients' extensions, by spelling their first names, or by spelling their last names, this sets the default mode. In the subscriber conversation, subscribers can switch between addressing by name or ID by pressing “##” but they cannot change between spelling by last name first or by first name first. That must be set via the SA/AA or using BulkEdit.
Limit message addressing list to this name lookup handler. For Unity 5.0(1) subscribers can have the scope of their address searches (by name or extension) limited to membership name lookup call handler. Selecting a name lookup handler here will prevent subscribers with that assignement from addressing messages not visible outside that name lookup handler.
Address message, then record it. Changes the defautl to address messages first then record as opposed to recording first then addressing.
Send message when subscriber hands up or is disconnected. By default when a message is addressed and there's some recording, if the user hangs up, the message is sent. You can change the default to insteat throw away the message (or use Dropped Call Recovery feature to keep a temporary copy of it) by changing this value.
Encrypt all messages marked private: If secure messaging is enabled, this value can dictate that any message marked private is also encrypted such that external users will never be able to listen to it even if forwarded off site.