Message delivery system using message metadata

A system comprising:

• a storage unit, storing a plurality of messages yet to be electronically sent, each of said respective messages including associated metadata describing information about the respective message, said storage unit including:
• a local storage which non-persistently stores a first amount of information describing imminent messages, which are more likely to be sent within a predetermined period of time, and non-persistently storing a second amount of information, less than said first amount of information, describing non-imminent messages which are less likely to be sent within the predetermined period of time,
• a remote storage, which persistently stores additional information about at least said non-imminent messages such that information about at least said non-imminent messages is being stored in both the local storage and remote storage;
• and
• a processor, operating to determine information about each respective message in the plurality of message, and to manage an amount of information about each respective message in the plurality of messages that is stored in the local storage versus in the remote storage.