If you've recently installed this version of the Firmware on your Sonicwall EMail Security Appliance, upgrade to 7.1.2 as soon as possible! This version has a serious bug that eats up disk space and randomly causes the appliance to stop responding.
There is also a chance that the Spam Fingerprint database is corrupted. One symptom of this corruption is the ratio of Likely spam is much higher than the Definate spam. If you run into this issue, contact Sonicwall Tech support so they can give you instructions on how to repair the corrupted database.