As someone else suggested in this thread, we do get a pretty incredible volume of applicants. If it's clear from the resume that it's not a match, we generally don't contact the applicant. In an ideal world we would prefer to get back to each person who submits a resume - but the volume is such that we have decided not to do that.
However, we do carefully read every application. And once we engage with an applicant, we always respond and we respond promptly.
At some point, as your company grows, your recruiters may trawl the backlog of past applicants and decide to give me another look. It then becomes a question of how I remember my interactions with you. If you didn't have the time or systems to give me even the most cursory of feedback, you best believe I won't have the time to give you that either. So sure, there are hundreds of names, flying at you. But those names are people. A templated rejection letter is really the least you can do. Most applicant tracking systems support this.
Ad-hominem.
> It's as a curtsey but don't think it's necessary.
The job hunt process is lubricated with politeness. Both employer and employee should want to make a good impression on each other; like on a first date. I can't imagine a situation where courtesy was more necessary than that. More so, when it costs next to nothing to send out an AUTOMATED email
1) Acknowledging receipt of an application and thanking the candidate. [Enables the candidate to keep records in a busy life]
2) Informing them you've moved on, and how soon they are allowed to apply again [Typically >3months].