There is currently no way to exclude specific contacts from the getting a CES.
This functionality should be added.
We have some customers that have specifically requested not to get the survey anymore, and there is no way to do this if we open a support ticket for them. A cumbersom workaround is needed.
First, we already had a work flow to handle ticket allocation - this would send out automatic notifications if new tickets were generated. If you don't have a workflow in place already, create one at the 'New' stage.
Your first branch should check if a contact associated with the ticket has an email address thats the same as the helpdesk that you're trying to exclude from sending surveys. If a mail is coming from one of those systems, move we move the ticket to a new stage called 'to delete', and we purge those tickets on a weekly basis.
Obviously, this won't work if you're receiving legit mails from those contacts, but the same theory should allow you to exclude tickets with a particular title (i.e. email subject) for example if they follow a pattern.
