All messages assigned to a mailbox are stored on the hard disk in the pSeries computer. If one mailbox accumulates a lot of messages (or even a few very long messages), the messages can take up a large amount of disk space.
Blueworx Voice Response includes two tools to help you control how much disk space messages can use. One controls the maximum length of a message. The other controls how many messages an application can store in a single mailbox.