A large number of files have accumulated in the Symantec Mail Security for Microsoft Exchange (SMSMSE) temporary directory, default location C:\Program Files (x86)\Symantec\SMSMSE\%Version%\Server\Temp directory.
When a file is written to the temporary directory in SMSMSE for scanning, the Microsoft Exchange Transport service is responsible for deleting the file after the scan verdict is returned. If the Microsoft Exchange Transport service does not have access to delete the files after the verdict is returned, files will accumulate in the directory over time. The Microsoft Exchange Transport service runs under the security context of the Network Service account.
Add full control to the SMSMSE temp directory for the Network Service account.
To add full control to the directory for the Network Service account:
After taking the above steps, the .tmp files will no longer accumulate in the directory. It is safe to delete the existing .tmp files from the directory.