Did you ever have one of those conversations that somehow just never ended? They trickle on over days or weeks, when they should have been over ages ago.
An email came in from a customer saying, "Hi, I'd like to do X, but I'd like to do it with Y turned off in Z configuration. Is that feasible?"
A newbie support guy responded with, "I'm not sure. I'll do some research and get back to you."
The support guy went to development and explained what the customer wanted.
The developer said, "well, that won't work, but what's he trying to do? Maybe there's another way."
The support guy took that info to the customer, who described what he was trying to get out of it.
The support guy went back to the developer, who said, "Hmm.... yeah, I don't think that's possible in this build."
Support guy went to the customer and said, "We're not sure if we can do it. I'm doing more research."
You can see where this is going. Or, more precisely, you can see where this is not going. Everyone involved is trying to do the right thing. The customer wants to accomplish something, and the developer and support guy are trying to make it happen, even though the product doesn't accomplish that in any way anyone can think of.
The problem is that until someone along the line says, "No, that's not possible," then the conversation won't end. There will be more research, and ideas, and thinking, and trying. And that's great, if it's really feasible. But if the product really doesn't support it (and in this case, the product really didn't support it), then it's better to end the conversation with a simple no. Offer alternatives (outside the system), and put the customer into the feature request queue, if that's appropriate, but be definitive.
When the answer is "yes, that totally works and here's how," then it's easy to be definitive. When the answer is "no," however, it's a lot harder. No one wants to hear no, and no one wants to say no. However, if the answer is eventually going to be "no," then it's better to get it early on. Better a "no" than a dragging on the issue and then a "no".
Wherever possible, be definitive. A quick and accurate no hurts a long less than a dragged out no. Get in, get out, and move on. Your customers will have more confidence in you, and you won't have wasted anyone's time.