A couple of years ago I was involved in recruiting new staff to my organisation. The official policy was not to reply to those applicants who didn't even make it to interview. Call me a rebel if you like, but I flouted that policy and would certainly do so again. More recently I've was applying for jobs, and faced the same type of policy from the other side of the fence.
Leaving aside the rudeness of such a policy, I want to look at why this is bad strategy and a missed opportunity.
Applying for jobs takes most people hours. Often you’ve not heard a great deal about an organisation but you scour their website, get your head round their passion, mission, vision and values, you imagine yourself in the post, how you would suit it and daydream about what it might be like. In short you grow an affinity with it.
At other times it’s already an organisation you already care about and are involved in. If it's a charity you might occasionally donate money. If it's a business you might occasionally shop there or use their services.
Either way when after all your hard work the organisation in question can’t even be bothered to take a minute to send you a rejection email / letter, you can feel quite put out. All that interest and connectedness you feel with them dissipates because of their rudeness.
This is particularly bad choice for networking organisations, which are built by making good contacts, developing them and growing connections. It's also a bad choice for charitable organisations who are potentially putting off potential donors, or retail organisations who are losing (potential) customers. Can anyone afford to waste that for the sake of a quick generic email? It's even possible that whilst the applicant wasn't suited to that particular role, they might excel in another role for you down the line.
No-one likes rejecting applicants, but a quick email or even a letter thanking them for their interest maintains the connection they feel. They’re disappointed of course, but people get used to that job hunting. The validation, however small, is important and maintains the opportunity to make the most of what the person does have to offer in future.