The Local System account does not have permission to write to the application event log which prevents the Symantec Mail Security for Microsoft Exchange service from starting.
Add permission to allow the local system account to write to the application event log by modifying the custom security descriptor.
Warning: This process can prevent your server from booting correctly if the steps are not performed correctly. Symantec recommends backing up your registry prior to performing these steps. To back-up your registry automatically, use the tool in this document ‘Backing up the Windows registry’.
Open the registry editor (Start > Run >
Open the registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Eventlog\Application\CustomSD.
For each of the following security descriptors that are not present in the key add them to the end: