We are currently implementing Servicedesk 7.5 SP1 and there is no way to email a link to the Customer Survey if the tickets is selected as part of the randomizaion rule. It is quite unrealistic to expect end users to go into the ProcessManager console, open My Task List, expand the tasks section for SD.CustomerSurvey, and click the Take Survey link.
Most users can't figure out how to use the console to create their own tickets, how can you think they would be able to perform this much more complicated task?