At its core, System Center Configuration Manager is a file delivery system, distributing logs, statuses, and inventory details throughout the organization. These files contain information critical for ConfigMgr work properly and through Windows and SQL services, information is consumed and acted upon. For the files to be acted upon, they end up in various inboxes (folders) in the ConfigMgr system.
A good indication of when problems exist in the system is certain inboxes will start filling up with files. Sometimes the inboxes will fill due to corrupted files, sometimes due to misconfigurations, and sometimes due to issues in the environment and infrastructure. Actually, there is a never-ending list of reasons why problems might exist, so a good practice is to watch the numbers of files in each inbox. When the numbers start to increase at an alarming rate, you'll know that it's time to start troubleshooting and sifting through applicable log files. To do this you need to know where each inbox exists and what to which service each inbox is associated with.
Fortunately, a good friend of mine and MVP, Rob Marshall, has released a valuable tool that takes much of the guesswork out of the equation. ConfigMgr Inbox Monitor allows you to view the file counts in the inbox folder structure for ConfigMgr. The tool provides a birds-eye view of the total amount of files in each of the inboxes, allowing you to take action should the number of distributed files be out of scope.
ConfigMgr Inbox Monitor is free and available for download from the TechNet Gallery.
Download: ConfigMgr Inbox Monitor