You do not need Message Networking to network multiple Avaya Aura® Messaging systems. You can optionally use Message Networking as an LDAP server database to update the local and remote user database and to perform user lookup. Messaging Networking does not have any role in delivering the messages if messages are sent from Avaya Aura® Messaging to Avaya Aura® Messaging.
Message Networking is required when you network the messaging systems like Audix, Aria, and other legacy systems to the Avaya Aura® Messaging system. To network with the traditional voice messaging systems, Avaya Aura® Messaging uses Message Networking. Message Networking not only updates the user database and performs the user lookup but also delivers the messages.
Avaya Aura® Messaging supports a maximum of 100,000 remote users, irrespective of whether Message Networking is used to connect the Avaya Aura® Messaging system to other messaging systems.