The obvious is when a customer is satisfied with the resolution of an issue. Very simple when the customer calls in and you send them an answer that solves their problem. 

It gets a little ambiguous on how to handle a feature request. For example if the customer in a request asks for the offering to do more than it can, should you leave it open until it is resolved (potentially years) or close it out and ask them to propose and idea. 

I am struggling with how to handle these 'longer term' requests. Close then reopen when relevant?