Scott, we are running Exchange 5.5 and something is eating up disk space on the c: drive. What could be causing this and what can I safely delete to free up space? Also where do you set up the program so that it will notify us who is receiving infected files via e-mail?
The excessive space consumption could be caused by any number of things, including a build-up of transaction logs or message tracking logs, or by a message that is caught in some sort of a mail loop. I would examine your C: drive folder-by-folder, or perhaps do a search for files created in the last day or two. This should help you determine what file(s) are consuming space.
As far as safely deleting things, definitely do not delete any of the transaction logs or databases. If you take a full online backup of your Exchange information stores, the transaction logs will get automatically purged once they have been successfully committed, and this will free up space.
Exchange itself does not include antivirus software and, as such, has no mechanism to alert you as to who is receiving (or for that matter sending) infected files. You'll want to look into an Exchange-aware antivirus software package, such as Trend Micro's ScanMail for Exchange, Sybari Antigen, etc.